Tech Info - ZR1 Corvettes modifications and Rebuild Tricks
 

This thread includes various modifications/refurbishments of several corvettes including three 1990 ZR1s, one 1991 ZR1. one 1995 ZR1, and one 1990 L98 corvette.
The various modifications and refurbishments are described in detail with complete photo coverage for each corvette.
Some duplicate modifications are included with different photo coverage and details :thumbs:
Each of the six corvette coverages starts with a complete detail summary of modifications and refurbishments.

Individual Corvette modifications/refurbishment SUMMARY
Post 62 -1990 (#2067) LT5 Top End Rebuild (C5 Z06/Wilwood Brakes, SW Headers, Aluminum Radiator)
Post 76 - 1991 (#1427) LT5 Rebuild (C5 Z06/Wilwood Brakes, SW Headers, Ron Davis Radiator)
Post 119 - 1990 (#3032) LT5 Top End Rebuild (Fluidyne Radiator)
Post 133 - 1990 (#0072) LT5 Top End Rebuild (Ron Davis Radiator)
Post 230 - 1995 (#0186) LT5 Specific Top End Rebuild (C5 Z06/Wilwood Brakes, Fluidyne Radiator)
Post 261 - 90’ (#8550) Corvette (L98) Modifications (SW Headers, Wilwood Brakes, Ron Davis Radiator)

The 91' ZR-1 (LT5) Modifications/Rebuild Tricks starts with post 76 (Including 500+hp).
See Section C and Section E Below for specific details related to the 1991 ZR1 modifications.

The individual corvette discussions is followed by specific technical information associated with all ZR1 corvettes.

Any word or group of words underlined are Left Clickable Links

A. See Technical Index which is an INDEX of Technical Posts in this thread.

A Specific Technical INDEX is provided at the bottom of this post recognizing the Index of this Thread in A above is mostly Date based and topics created as ZR-s/LT5s were Restored/Modified. This Specific Technical INDEX (BELOW in this Post) includes ALL posts in this Thread.


B.The Solutions index is an index for Corvette Technical Posts including those Posts in the C4 ZR-1 Discussion Section and specific posts in this thread.

Post 102. SOLUTIONS Overview and Ebay Searches
Post 103. ZR1 General
Post 104. ZR1 Electrical
Post 105. ZR1 Engine
Post 106. ZR1 Drive Train
Post 107. Awesome
Post 108. ZR1 Engine Fuel, Lubrication, Cooling, and Exhaust
Post 109. ZR1 Specifications, Restorations, Air, Audio, Lifts, and Road Trips
Post 110. ZR1 Engine (LT5) Bolts and Hydraulics

C. See LT5 Specific Rebuild Tricks which includes complete photo coverage of an LT5 Rebuild including engine removal and installation in this thread.

D. Related other threads found in the C4 ZR-1 Discussion Section are as follows:

Tech Info - LT5/ZR-1 Technical Calculations LT5 Technical Calculations
Tech Info - LT5 Eliminated Systems LT5 Eliminated Systems
Tech Info - Marc Haibeck on LT5 Eliminated Secondaries and Associated Anomalies
Marc Haibeck on LT5 Eliminated Secondaries and Associated Anomalies
Tech Info - LT5 Added Systems LT5 Added Systems
Tech Info - Removing a Pressed In Fitting Removing a Pressed In Fitting
Tech Info - LT5 New Rebuild Issues (Lifters and Camshafts) LT5 New Rebuild Issues (Lifters and Camshafts)
Tech Info - LT5 Timing Chain and Engine Pulses LT5 Timing Chain Calculations
Tech Info - LT5/ZR-1 Technical Calculations LT5/ZR-1 Technical Calculations
Ben's 90' Complete Restoration including the rebuild of an LT5 bottom to top Ben's 90' Restoration

HELP threads:
For additional Help Posting Photos Creating Albums and Posting Photos
For additional Help in creating Posts using Link References Reference Link Names

E. Overview of ZR-1 (LT5) Modifications/Rebuild Tricks (500+hp)

https://cimg2.ibsrv.net/gimg/www.cor...dd214abb56.jpg

1. Systems added included LT5X Head Studs and an Oil Catch Can for the PCV system.
2. Several systems were eliminated including the secondaries, TB coolant, Air Injection system, and Vacuum system.
3. LT5 engine was highly ported top end with reground camshafts installed.
4. Included in this thread are the modifications of a 90' Corvette (L98).

1. LT5X Studs (Randy Woods)........................................ ...2. 200 Amp Alternator
https://cimg0.ibsrv.net/gimg/www.cor...c584c677d8.jpghttps://cimg6.ibsrv.net/gimg/www.cor...0e5af405a3.jpg
3. Eliminated Systems (Secondaries)............................4. Plenum, TB Coolant eliminated
https://cimg7.ibsrv.net/gimg/www.cor...d3c6caec5d.jpghttps://cimg8.ibsrv.net/gimg/www.cor...8c4aff133e.jpg

5. Reground Camshafts (Pete)...........................6. Air Horn, Plenum, IH, Head Porting (Locobob)
https://cimg6.ibsrv.net/gimg/www.cor...3b47627403.jpghttps://cimg7.ibsrv.net/gimg/www.cor...de1ca2ceac.jpg

6. Specific Technical INDEX presently being created
Post 280 - Specific Technical Index

7. Technical Index Post Updates
Post # ………………………..Date

Last UPDATE of post 1 Feb, 2024

General Technical Index By Restoration
 

Technical Index

INDEX of Technical Posts for ZR-1 (LT5) Modifications/Rebuild Tricks.
Left click on any Link Name as described below.

This Index is organized by Headings from General Information (Posts 3 - 6) to Engine Cooling (Posts 7 - 14), Lifting (Posts 15 - 16), Lubrication (Posts 18 - 20), Camshaft Timing (Posts 21 - 28), Top End Restoration (Posts 29 - 34), Transmission (Posts 35 - 39), Drive Train & Brakes (Posts 40 - 44), Exhaust System (Posts 45 - 47), Electrical/MISC (Posts 48 - 59), Audio (Posts 60 - 61), 1990 LT5 Specific Rebuild Tricks (Posts 62 - 69), Bling and Performance (Posts 70 - 75), 1991 LT5 Specific Rebuild Tricks (Posts 76 - 96), TIPS (Posts 97 - 99), Tools and LT5 Differences (Posts 100 - 101), Solutions (Posts 102 - 110), Ebay Searches and Acronyms (Post 111), Additional Information (Posts 113 - 117), Miscellaneous Topics (Posts 118 - 130), Forum Albums and Resizing Photos(Posts 131 - 132), Other Topics (Posts 133 - 140), Questions and Answeres (Posts 141 - 145), LT5 Eliminated and Added Systems (Posts 146 - 148), LT5 Systems (Posts 149 - 180), 1991 LT5 Spare Engine Rebuild/Assembly (Posts 181 - 200), ZR-1/LT5 Technical Calculations, (Posts 201 - 215), Eliminated Systems and Added Systems (Posts 216 - 220), LT5 Lifters, Camshafts, and Valves (Posts 221 - 229), 1995 Top End Restoration (Posts 230 - 250), Summaries (Posts 251 - 260), Standard Corvette (L98) (Posts 261 - 280).

Individual Corvette modifications/refurbishment SUMMARY
Post 62 - 1990 (#2067) LT5 Top End Rebuild (C5 Z06/Wilwood Brakes, SW Headers, Aluminum Radiator)
Post 76 - 1991 (#1427) LT5 Rebuild (C5 Z06/Wilwood Brakes, SW Headers, Ron Davis Radiator)
Post 119 - 1990 (#3032) LT5 Top End Rebuild (Fluidyne Radiator)
Post 133 - 1990 (#0072) LT5 Top End Rebuild (Ron Davis Radiator)
Post 230 - 1995 (#0186) LT5 Specific Top End Rebuild (C5 Z06/Wilwood Brakes, Fluidyne Radiator)
Post 261 - 90’ (#8550) Corvette (L98) Modifications (SW Headers, Wilwood Brakes, Ron Davis Radiator)

GENERAL
Post 3 - LT5/ZR-1 Fluids
Post 4 - General Bolt Length, Bolt Torque, Loctite, and Tools
Post 5 - Use of thread Lubricants, Loctite and Sealants
Post 6 - Manual Supplement, Secondary Diagnostics, Sensors, and Prom Codes.

ENGINE COOLING
Post 7 - Thermostats, Fans, Water Pump, and Radiators
Post 8 - LT5 Radiator and Initial Coolant Fill Tricks
Post 9 - HVAC Temperature Display And Radiator Efficiency Test Runs
Post 10 - Water Pump, Coolant Temperatures, and Coolant
Post 11 - Radiator Debris Screens
Post 12 - Getting The Air Out of the Coolant System
Post 13 - TB Coolant Discussion
Post 14 - Coolant Characteristics (Mix, Pressure, Elevation)
Post - Eliminated TB Coolant Photos and Details

LIFTING
Post 15 - Lifting The LT5
Post 16 - Lifting and Towing the ZR-1
Post 17 - Kudos

LUBRICATION
Post 18 - Engine Lubrication System Functional Discussion
Post 19 - LT5 Lubrication Tricks and Replace Dip Stick Handle
Post 20 - Potential Oil Leaks and the OPRV Cover Plate

CAMSHAFT TIMING
Post 21 - LT5 Camshaft Specifications and Camshaft General Timing (pinning)
Post 22 - LT5 Camshaft Specific Timing (degree wheel)
Post 23 - LT5 Camshaft Timing Additional Tricks
Post 24 - LT5 Timing Diagrams and Timing Chain Effective Lengths
Post 25 - LT5 Timing Chains and Sprockets
Post 26 - Setting/Installing the Chain Tensioners Tricks
Post 27 - Cam Cover Installation Tricks
Post 28 - PCV system (Need for Oil Catch Can)

TOP END RESTORATION
Post 29 - Plenum Pull
Post 30 - LT5 IH (RC Injectors), Fuel Rails, Plenum Install Tricks
Post 31 - Vacuum Systems 90' and 91' (Secondary and Cruize/HVAC)
Post 32 - Eliminated IH Housing and Throttle Body (TB) Coolant system Tricks
Post 33 - Eliminated Secondary Throttles/shafts Tricks
Post 34 - Stainless Steel Air Box and Air Filter (L98 and LT5)

TRANSMISSION
Post 35 - Pilot Bearing
Post 36 - ZR-1 Transmission Install and Lift Tricks
Post 37 - Vibration Issues Diagnosis
Post 38 - Throwout Bearings and Clutch Forks
Post 39 - C4 Beam Plates and Installation

DRIVE TRAIN AND BRAKES
Post 40 - Tires and Selective Ride Control
Post 41 - ZR-1 (90' and 91') Wilwood Rotors and C4 to C5-Z06 Conversion
Post 42 - Going from 3:45 to 4:10 Differential
Post 43 - LT5 Final Inspection including, Testers, Brake Tricks
Post 44 - Accessories

EXHAUST SYSTEM
Post 45 - Exhaust System Replace with Headers
Post 46 - Exhaust Headers Locking Bolt Tricks
Post 47 - Installing the LT5 with Headers and the O2 Sensors Functionality

ELECTRICAL/MISC
Post 48 - 1990 and 1991 Fuses/Additional 12V Connector
Post 49 - Backup Tail Light Switch and Alternators
Post 50 - Replacing the Windshield and Wiper Motor
Post 51 - CMHSL LED, Full Power Key and Alternator Pulley
Post 52 - Starter, Starter Relay, Wiring Harness, Battery, and Plugs Tricks
Post 53 - Electrical Ground Connections and Installing Starter Relay
Post 54 - Ignition Key Codes and Clearing 1990 INFL REST Codes
Post 55 - ALDL Fault Code Reader/Eraser
Post 56 - ABS, Ride Control, CCM, SIR Code Definitions
Post 57 - ZR1 90'-95' ECM Interchangeability and CODES 90' TO 92'
Post 58 - Recharging The AC System
Post 59 - Crankshaft Sensor and Camshaft Sensor

Audio
Post 60 - Bose Speaker Amp Options TIPS
Post 61 - Typical Low Mileage ZR-1 Restoration Starting With Audio

1990 (#2067) LT5 SPECIFIC TOP END REBUILD TRICKS
Three 1990 Top Ends were rebuilt and best tricks linked here
UL LOSE, UWLNTWN, ULNOTWN
Post 62 - 1990 (#2067) LT5 Top End Rebuild (Including Wilwood Front Brakes)
Post 63 - Removing Plenum (including the 10 minute Plenum Removal)
Post 64 - Inspection, Testing and Reconditioning the Valley, Starter, and Coils
Post 65 - INFL REST grounds and Alternator Connector Boot
Post 66 - Secondary Functional Test and Reconditioning the Secondary Actuators
Post 67 - Removing Cam Covers (Engine In Car) for Inspections of Camshafts
Post 68 - Eliminating TB Coolant and Air Induction, Added Oil Catch Can and Painting
Post 69 - Summary of 90' Reconditioning/Modifications

BLING AND PERFORMANCE
Post 70 - Bling (Carter and Others)
Post 71 - 1991 ZR-1 (LT5) Performance
Post 72 - 1991 ZR-1 (LT5) Modifications (500+ HorsePower)
Post 73 - Summary of LT5 Restorations
Post 74 - What Fluids to use in the ZR-1
Post 75 - 1990 ZR-1 (LT5) Performance/Reconditioning/Modifications

1991 LT5 SPECIFIC REBUILD TRICKS
Post 76 - 1991 (#1427) LT5 Rebuild Tricks
Post 77 - New Piston Sleeve and Piston
Post 78 - Timing Chain Guides Installation
Post 79 - Timing Chain Idler Sprocket Lubrication and Installation
Post 80 - Front Cover, OPRV Cover, Water Pump, Harmonic Balancer
Post 81 - Oil Pan (Oil level and Knock Sensor), Flywheel, Clutch, Bell Housing
Post 82 - Checking for Oil Leaks/Making your own SS Braided Oil Lines
Post 83 - Installing Heads and Camshafts
Post 84 - Camshaft Timing
Post 85 - Camshaft Timing (Locking the Camshafts) and Camshaft Lubrication
Post 86 - Cam Covers (Filters and Wear Strips)
Post 87 - Installing Headers and Exhaust
Post 88 - Installing Engine In ZR1
Post 89 - ECM Chip and Other Electrical Connectors
Post 90 - Alternator, AC Pump, Power Steering Pump
Post 91 - Installing Fuel Rails and Ignition Coils
Post 92 - Installing Plenum, TB, and Air Cleaner
Post 93 - Filling With Coolant and the Air Locked Water Pump
Post 94 - Preliminary Starting Checks
Post 95 - Engine Running First Time Checks
Post 96 - Summary of 91' Reconditioning/Modifications

TIPS
Post 97 - Checking for abnormal noise and leaks LT5 engine
Post 98 - Number 8 Spark Plug Removal and Test Drive with Jeff Gordon
Post 99 - Adapting 91 IH to 90 Heads

TOOLS AND LT5 DIFFERENCES
Post 100 - ZR-1 and LT5 Tools
Post 101 - Differences between 90', 91' and 95' ZR-1s and Engines

SOLUTIONS
Post 102 - SOLUTIONS Overview and Ebay Searches
Post 103 - ZR1 General
Post 104 - ZR1 Electrical
Post 105 - ZR1 Engine
Post 106 - ZR1 Drive Train
Post 107 - Awesome
Post 108 - ZR1 Engine Fuel, Lubrication, Cooling, and Exhaust
Post 109 - ZR1 Specifications, Restorations, Air, Audio, Lifts
Post 110 - ZR1 Engine (LT5) Bolts and Hydraulics
Post 111 - Ebay Searches and Acronyms
Post 112 - Kudos

ADDITIONAL INFORMATION
Post 113 - Fuel Trim and Closed/Open Loop Operation
Post 114 - Kudos
Post 115 - Question Regarding Air Locked Water Pump
Post 116 - LT5 Air Locked Water Pump Simplified
Post 117 - LT5 PCV System

Miscellaneous Topics
Post 118 - Three Things To Do For A No Start
Post 119 - Last 1990 (#3032) ZR-1 Sold and ZR1 Inspection TIPS
Post 120 - Thermostats, Fans, Radiators and Coolant Filling
Post 121 - Finding A Vacuum Leak
Post 122 - Wilwood C5 Z06 Brake Conversion with Sawblades
Post 123 - Rebuilding Belt Tensioner
Post 124 - Checking Lubrication System
Post 125 - SS Braided Oil Cooler Hoses and Fittings
Post 126 - Getting The Air Out Of Coolant System
Post 127 - Replacing Bolts In Various Components and Use of Loctite
Post 128 - Activating Secondaries
Post 129 - Engine Has To Be Pulled To Time Camshafts
Post 130 - Cam Cover Filters

FORUM ALBUMS AND RESIZING PHOTOS
Post 131 - Resizing Photos for Forum Posts and Creating Reference Links
Post 132 - Using Forum Photo Albums……Resizing photos

Other Topics
Post 133 - Minimum Restoration of a 1990 (#0072) ZR-1
Post 134 - Continued........Minimum Restoration of a 1990 (#0072) ZR-1
Post 135 - Replacing the Heater Core and Heater Hose Connection
Post 136 - Hose Clamps, Screws/U-Nuts, Magnetic Sockets
Post 137 - Using Permatex and Headliner Glue
Post 138 - Showroom Mats for ZR-1s
Post 139 - Bose Speaker Amps and CDM Replace
Post 140 - Cylinder Numbers and Firing Order

Questions and Answeres
Post 141 - Exhaust Hangers Question
Post 142 - Exhaust Hangers Defined
Post 143 - Kudos
Post 144 - Replacing the Coolant (LT5)
Post 145 - how often do you change your oil and other fluids

LT5 Eliminated Systems
Post 146 - LT5 Eliminated Systems

ZR1 Added Systems
Post 147 - ZR1 Added Systems including Differential Case Drain
Post 148 - Elite Engineering Oil Catch Can

LT5 Systems
Post 149 - Engine with bottom end intact
Post 150 - How to Remove Injector Housing Coolant Manifold Torx-30 Bolts
Post 151 - Starter Rebuild
Post 152 - Clutch Master and Clutch Slave Cylinder
Post 153 - Spark Plug Wire Separators
Post 154 - The Battery Disconnect Switch and Having an Operational Secondary Full Power Switch
Post 155 - Six things I ALWAYS do on any LT5.
Post 156 - Replacing the Serpentine Belt
Post 157 - LT5 Engine Cooling Issues on Hot Days
Post 158 - LT5 Engine Optimum Operating Temperatures
Post 159 - Checking Camshaft Timing Engine In Car
Post 160 - PCV Upgrades
Post 161 - Secondary Chain Guide Rattle
Post 162 - Cam Cover Chain Guides, Filters, and A136
Post 163 - Camshaft Identification
Post 164 - MSD 8224
Post 165 - Painting Top End
Post 166 - Battery Disconnect
Post 167 - 1990 and 1991 Plenums and TB Coolant Blocking at IH
Post 168 - Installing a Ron Davis Radiator and Testing
Post 169 - Reserved 21
Post 170 - Abbreviations
Post 171 - Reserved 23
Post 172 - Reserved 24
Post 173 - Reserved 25
Post 174 - Reserved 26
Post 175 - Reserved 27
Post 176 - Reserved 28
Post 177 - Reserved 29
Post 178 - Reserved 30
Post 179 - Horsepower Losses from Angular Acceleration of Rotational Mass
Post 180 - Tools to Carry in the ZR-1

1991 LT5 Spare Engine Rebuild/Assembly
Post 181 - The Rebuild and Assembly of a 1991 Spare LT5
Post 182 - Bottom End Restoration Including Oil Pan
Post 183 - Starter Rebuild
Post 184 - Restoration of the Ignition Coils, plugs, Wires
Post 185 - Painting Plenum, TB, Injector Housing and Cam Covers
Post 186 - Restoration of the Secondary System including the linkages
Post 187 - Restoration of the Injectors
Post 188 - Restoration of the Heads
Post 189 - Head Installation
Post 190 - Finding TDC and Locating 51 deg BTDC
Post 191 - Water Pump, Power Steering Pump, and Injector Housing Installation
Post 192 - Injector Housing TB Coolant Blocking
Post 193 - Alternator and AC Compressor Installation
Post 194 - Camshaft Timing
Post 195 - Installation of the DIS Module
Post 196 - Installation of Secondary Vacuum System
Post 197 - Plenum Installation
Post 198 - Installation of Flywheel (Including Pilot Bearing), Clutch and Bell Housing
Post 199 - Removal and Installation of Harmonic Balancer/Front Cover
Post 200 - Compression Testing

ZR-1/LT5 Technical Calculations
Post 201 - ZR-1/LT5 Technical Calculations
Post 202 - Tech Info - LT5 Horsepower and Torque Calculations
Post 203 - Tech Info - ZR1 Differential Gearing and Vehicle Speed Calculations
Post 204 - Tech Info - ZR1 Wind Force, Rolling Resistance, Drivetrain Loss Calculations
Post 205 - Tech Info - LT5 Camshaft Timing Calculations
Post 206 - Tech Info - LT5 Pressure Drop In Oil Lines Calculations
Post 207 - Tech Info - RC SL4-205 injectors (500+ hp) Calculations
Post 208 - Tech Info - LT5 Summary of Camshaft Timing
Post 209 - Tech Info - LT5 Timing Diagrams
Post 210 - Tech Info - L98 Frisbee Horsepower
Post 211 - Tech Info - LT5 Coolant Flow Calculations
Post 212 - Calculating Alternator Pulley Diameter
Post 213 - Technical Calculations Reserved 1
Post 214 - Technical Calculations Reserved 2
Post 215 - Camshaft Compression of Lifter

Eliminated Systems and Added Systems
Post 216 - Eliminated Systems and Added Systems
Post 217 - Tech Info - Marc Haibeck on LT5 Eliminated Secondaries and Associated Anomalies
Post 218 - Tech Info - LT5 Added Systems
Post 219 - Elite Engineering Oil Catch Can Installation Details
Post 220 - Hans Meyer Check List with Additional Comments

LT5 Lifters, Camshafts, and Valves
Post 221 - Tech Info - LT5 New Rebuild Issues (Lifters, Camshafts, and Valves)
Post 222 - Lifters
Post 223 - Lifters and Valve Stem dimensions (reground valves)
Post 224 - Valve Stem Clearance Measurement Tool
Post 225 - Camshaft and Lifter Measurements (Stock and Regrind) all in inches
Post 226 - Valve Stem Clearance Measurements For Regrind Camshafts using Mellings JB 2236 Lifter
Post 227 - Regrind Camshafts Performance
Post 228 - Bad Z
Post 229 - Valve Stem Clearance Measurements For Stock Camshafts using Mellings JB 2236 Lifters

1995 (#0186) LT5 SPECIFIC TOP END REBUILD TRICKS
A 1995 Top End was rebuilt and best tricks linked here
Post 230 - 1995 (#0186) LT5 SPECIFIC TOP END REBUILD TRICKS
Post 231 - Clean Up of Valley, Installation of Battery Disconnect Switch and Coils
Post 232 - Installation of Rebuilt Starter, New Alternator, and Braided SS Oil Cooler Lines
Post 233 - Installation of Wilwood Rotors and C4 to C5-Z06 Conversion
Post 234 - Installation of New Secondary Port Vacuum System Lines
Post 235 - Installation of Reconditioned Injectors with New "O" Rings
Post 236 - New PCV Connections. Installation/Relocation of Plug Wires and New Spark Plugs
Post 237 - Blocking TB Coolant, Fluidyne Radiator and Thermostats
Post 238 - Reconditioning and Installation of Plenum with SS Allen Head Bolts
Post 239 - Addition of Billet Aluminum Power Steering, Water Pump Pulleys
Post 240 - New Rear Wheel Bearings and Half Shaft U-Joints
Post 241 - Rebuilt Black Label Transmission Installed and New Driveshaft U-Joints
Post 242 - Installation of Elite Oil Catch Can
Post 243 - Replacing the Coils
Post 244 - INJ1 Fuse Keeps Blowing
Post 245 - Under the Plenum
Post 246 - The Four Minute Plenum Installation
Post 247 - 1995 ZR-1 #186 with Haibeck Chip
Post 248 - K40 Front and Rear Radar Detection System
Post 249 - Oil Pressure Regulating Valve Cover Plate
Post 250 - All Aluminum Alternator Pulley

Summaries
Post 251 - Thermostat and Thermostat Housing Discussion
Post 252 - Operational Engine Stand
Post 253 - Buy High.....Sell Low
Post 254 - Windshields
Post 255 - Reserved
Post 256 - Bilstein Shock Applications and Self Alignment
Post 257 - Wheels
Post 258 - Winter Storage
Post 259 - Typical ZR-1 Restorations
Post 260 - Summary of ZR1 Restorations including 95' Crate Engine

Standard Corvette (L98)
Post 261 - 90’ (#8550) Corvette (L98) Modifications
Post 262 - Oil Cooler Modifications
Post 263 - Timing Chain Cover/Water pump Interference
Post 264 - Air Pump Eliminated
Post 265 - Aluminum Finned Oil Pan including New Milodon 18307 Oil Pump Pickup
Post 266 - Rebuilding Chrome Alternator
Post 267 - SS Air Intake
Post 268 - Installation of C4 Beam Plates
Post 269 - Oil Pan Drain Plug and Differential Case Drain
Post 270 - Wilwood 6 Piston Brakes with 13" Rotors and Wheel Alignment

Specific Summaries
Post 271 - Modifications Summary 5 ZR-1s
Post 272 - Crate Engine
Post 273 - 95' Drive/Half Shaft U-Joints, Rear Wheel Bearings
Post 274 - Cooler Termostats, Thermostat Modifications and Engine RPM
Post 275 - The Best Belt Tensioner Pulley
Post 276 - Air Filter Installation
Post 277 - Reserved
Post 278 - 30K mile Lt5 Parts Value
Post 279 - ZR-1 Check List
Post 280 - What To Look For When Buying A ZR-1

Additional Technical Information
Post 281 - The Improved LT5 Fuel Pressure Regulator
Post 282 - Changing Out Improved Fuel Pressure Regulator (IFPR)
Post 283 - Phil's (Jagdpanzer) Fuel Pressure Regulator Solution
Post 284 - New Secondary Port Throttle Vacuum System
Post 285 - Alternators
Post 286 - Cooler Thermostats, Thermostat Modifications, Engine RPM, and Fans
Post 287 - Replacing the Serpentine Belt
Post 288 - Water Pump Cavitation
Post 289 - Ron Davis Radiator Installation
Post 290 - Cayenne Pepper Keeps Mice Away
Post 291 - Reserved
Post 292 - Locating Relays Above Drivers Side footwell
Post 293 - Bypassing Clutch Safety Switch
Post 294 - Camshaft Abnormal Wear
Post 295 - Reserved
Post 296 - Oil Changes
Post 297 - VIN Number
Post 298 - Amsoil 10W-40
Post 299 - Infl Rest Inside The Car
Post 300 - Acceleration
Post 301 - ZR-1 Fluids
Post 302 - Kudos
Post 303 - Reserved
Post 304 - Loctite 518
Post 305 - Loctite 518/A136 Discussion
Post 306 - Fuel Pumps Billet Aluminum Connection
Post 307 - Removal of Front Bumper Facia
Post 308 - Reserved
Post 309 - Reserved
Post 310 - Parts Estimated Value
Post 311 - CD Player Lens Cleaner
Post 312 - Reserved
Post 313 - Reserved
Post 314 - Reserved
Post 315 - VATS Keys
Post 316 - Double Dunn Heads

Last UPDATE of post 2 Feb, 2024

LT5/ZR-1 Fluids
 

LT5/ZR-1 Fluids

HammerZR1 initiated this list of ZR1/LT5 Fluids and I added photos and additional information :thumbs:

ENGINE OIL (LT5) ................. TRANSMISSION OIL (ZF S6-40)..........DIFFERENTIAL OIL Limited slip

8.6 quarts (with filter change) .....4.4 pints - Castrol TWS 10W-60 ............3.2 pints - Mobil 1 - 75W-90 Gear Lube
Amsoil 10W-40 AMO Motor Oil
Bosch 3401 Filter
FRAM TG 3985 Filter
Mobile 1 M1-207 Filter
https://cimg8.ibsrv.net/gimg/www.cor...00970babe8.jpg...................https://cimg3.ibsrv.net/gimg/www.cor...7e39289f75.jpg..................https://cimg4.ibsrv.net/gimg/www.cor...e6438cbb72.jpg

https://cimg7.ibsrv.net/gimg/www.cor...0f5003d62d.jpg

Amsoil 10w-40 Recommendation/Analysis

Amsoil 10w-40

For L98 engine use Mobile 1 Synthetic 10W-30 and a Mobile-1 M1-111 Oil Filter.

See Notes below regarding oil change intervals.

Amsoil SAE 10W-40
Castrol 10W-60

1. CAPACITIES
Engine (LT5), with filter change...............8.6 quarts
Cooling System (ZR1), Initial Fill.......18.0 quarts
Manual Transmission (ZF S6-40)........4.4 pints
Differential (ZR1)............................3.2 pints

2. Fill and Drain Plug TORQUES
Oil Pan Drain Plug (14 mm Box wrench).....38 ft-lbs (5/8-18 Thread).
Actually a bit less torque with a bit of Permatex on the washer/threads.
The Oil Drain Plug is a Helicoil insert which is installed to reduce wear and tear on an Aluminum Thread.
A 14 mm open end flex head Ratchet works perfectly on Oil Drain Plug.

https://cimg9.ibsrv.net/gimg/www.cor...6e9b4d41a0.jpghttps://cimg1.ibsrv.net/gimg/www.cor...6db819b867.jpg

3. Manual Transmission Allen Plugs use 17 mm Allen Wrench (see Note D Below).
Fill Plug Allen wrench torque........26 ft-lbs
Drain Plug Allen wrench torque.....26 ft-lbs
Actually a bit less torque with a bit of Permatex on the washer/threads.

4. Differential Fill Plug use 3/8 inch Allen Wrench.
Always use a Fluid Pump when adding fluid to the Differential or Transmission.
Differential Fluid Change Intervals
https://cimg1.ibsrv.net/gimg/www.cor...1daabe9451.jpghttps://cimg3.ibsrv.net/gimg/www.cor...a9fff2227b.jpg

5. Adding the Differential Oil Drain Plug to the ZR1 differential is a great idea.
The original ZR1 differential has no drain plug and the only way to remove differential fluid is to suck said fluid from the differential Allen Head Fill Plug. See Item #4 LT5 Added Systems

Install item # 584029 DIFFERENTIAL DRAIN PLUG KIT can be obtained from Corvette Central (includes 1/8 inch pipe tap, 11/32 drill bit) Differential Drain Plug Kit

Use 1/8 inch Aluminum allen head pipe plug you have to purchase separately 1/8 inch allen head pipe plugs

The kit provides a template that puts the hole just left of the center bolt in the valley of the differential. Just drill the hole gently and the differential oil and any shavings will drain completely. Then tap and install 1/8 inch Aluminum allen head pipe plug with a bit of Permatex on the threads. Do not tap too deeply to make sure the pipe plug is tight and flush when finished.

Flush a bit with Mobile 1 75/90 gear lube after completing the tap before installing the 1/8 inch allen head pipe plug.

6. RADIATOR COOLANT
You want to only use the green coolant. They have it at Napa and it meets 1825M GM Spec.

For Zerex the first gallon is called Regular Green Coolant (GM 1825M), the second gallon is called Original Formula (GM 1825M). Zerex ZXRU1 is 50-50 and Zerex ZX001 is undiluted. The third gallon is NAPA coolant (GM 1825M).

https://cimg1.ibsrv.net/gimg/www.cor...7eaa25e0d2.jpgORhttp://ecx.images-amazon.com/images/I/31jb-ZubjrL.jpgORhttp://partimages.genpt.com/partimages/213967.jpg https://cimg0.ibsrv.net/gimg/www.cor...1217db4bfd.jpg



7. OIL FILTER
I concur with HammerZR1 on all fluids cited above except I am using the Mobile 1 M1-207 oil filter.
Mobile 1 M1-207 Oil Filter

8. BRAKE and CLUTCH FLUID
For brake and clutch fluid Dot 3 or Dot 4 (Prefer Dot 4).

Notes:
A. I change engine oil every 2,000 - 3,000 miles (5,000 miles if cross country driving).
B. ZF Doc says until someone invents a copper magnet, change the ZF S6-40 6-speed transmission oil at 10,000 - 12,000 mile intervals so as to minimize the amount of deposits of the suspended spent synchronizer material from collecting in critical component contact surface areas.
C. On previously owned cars/trucks, I change engine, transmission, differential fluid and coolant immediately upon purchase (extracting old brake/clutch fluid and cleaning brake/clutch fluid reservoirs). This assures proper fluid levels and reduces comtaminants accumulated over the previous life of the vehicle.

D. Be careful on inserting the 17 mm Allen Wrench into the Transmission Drain Plug. That Transmission Drain Plug often has road rash which prevents complete insertion of the 17 mm Allen. If not completely inserted you may strip the Allen part of the Drain Plug.
Snap-On 17mm Allen/3/8 socket

Dress up the Allen part of the Drain Plug and then tap the 17 mm Allen into the plug using a small hammer for full insertion before applying a torque on the 17 mm Allen Wrench to remove the Drain Plug. I use a box wrench that fits over the long end of the 17 mm Allen Wrench for additional leverage making sure you keep the 17 mm Allen Wrench fully inserted in the Drain Plug you are removing.

17 mm Allen Wrench
https://cimg2.ibsrv.net/gimg/www.cor...292323e743.jpg

E. Oil Viscosity.

Newer engines are built with tighter tolerances (use lighter oil).
High Mileage engines lose tolerances (use heavier oil).
Hot climates (hotter engines) thin oil (use heavier oil).
Cold climates (colder engines) thicken oil (use lighter oil).
Often starting colder engines (lighter oil).
Running engines for long hauls once started (use heavier oils).
Newer synthetic oils do not loose viscosity with use (use lighter oils).
In Fl or CA coastal (use heavier oils).
In SD winter ....definitley (use thinner oils).
Frequent oil changes (use thinner oils).
Infrequent oil changes (use heavier oils).

F. Changing Engine Oil on the LT5.
Let the engine sit over night so you can remove the oil filter without a mess as Mike suggests. Yes...some oil filters have a check valve of sorts but on Mobile 1 M1-207s the filter can be removed without any oil mess after sitting over night.

The LT5 engine and oil cooler will hold about 12 quarts of oil of which you drain about 8-9 quarts on an oil change.
So you get about 70 % of the old oil changed on an oil change. Next time you will get 70% of that 30% old old oil (9% of old old oil remaing), and on the third change you will get 70% of the 9% old old old oil remaining with 3% of old old old oil remaining. And so it goes :D

The oil pick up screen in the LT5 Oil Pan sits about 1/4 inch from the bottom of the pan (has nothing to do with changing oil :p). When you drain oil (depending on how the ZR1 is sitting) you will have about 1/4 inch of oil in the bottom of the oil pan that does not drain.

On a ZR1 just purchased I will change oil twice within a week or so of each change to get down to the 9% of original "unknown" oil remaining.

Last UPDATE of post 3 Sep, 2022

General Bolt Length, Bolt Torque, Loctite, and Tools
 

General Bolt Length, Bolt Torque, Loctite, and Tools

1. In General bolt correct length checks can be determined by inserting the bolt (without turning) to the threaded portion of the receiver. For an 8 mm bolt, you should have approximately 7/16 to 1/2 inch of bolt showing (11 to 12.7 mm or 13 to 16 threads on a 1.25 t/mm bolt).

2. General Maximum Bolt Torque for steel bolts in aluminum if bolt torque is not specified.
Always use the correct size Drive Torque Wrench (1/4" Drive, 3/8" Drive, 1/2" Drive).
89 in-lbs on 6 mm bolts
19 ft-lbs on 8 mm bolts
30 ft-lbs on 10 mm bolts
40 ft-lbs on 12 mm bolts

LT5 Bolt Charts with suggested bolt torque, loctite and antiseize application information are included above. The free chart from Jerry's Gaskets which provided the basic LT5 component bolt sizes has been considerably modified into two charts above. The charts have been organized by function.

https://cimg3.ibsrv.net/gimg/www.cor...a3209de80c.jpg
https://cimg4.ibsrv.net/gimg/www.cor...4dcc4fd641.jpg

3. Loctite.
Red loctite 262 on all bolts except oil pan bolts, plenum bolts or anything you think you might remove a couple times. Use Blue loctite 242 on those items (Except SS Plenum and SS Cam Cover Bolts). Use Loctite 565 on sensors, switches, fittings. Use anti-zieze on plugs and injector housing coolant pipe bolts (on any stainless steel bolts) :mrgreen:

Nothing on new head bolts. Actually I use antisieze on Header Bolts with Stage 8 Header Bolt Locks.
Always use Stage 8 Exhaust Header Bolts with locks (Headers Only). Do not have to torque the Header Bolts too much as the locks will assure the bolts do not loosen (torqued header bolts into aluminum which area gets very hot makes removal of bolts at any time difficult). You can also use an Allen wrench on Stage 8 Bolts.

Use a bit of antiseize on Header Bolts with the Stage 8 Locks. Also use a bit of antiseize on all spark plugs.

https://cimg4.ibsrv.net/gimg/www.cor...c8a37cf082.jpg

4. Hydraulic Fitting Size comparison.
AN (Army and Navy).....-2.........-3...........-4.........-5.........-6..........-8........-10.......-12
Tube OD (Hose ID).......1/8".......3/16"...... 1/4".......5/16".....3/8".......1/2"......5/8"......3/4"
SAE thread size...........5/16-24..3/8-24.....7/16-20..1/2-20...9/16-18..3/4-16...7/8-14..1-1/16-12
Pipe thread size (NPT)..............1/8-27.....1/4-18................3/8-18....1/2-14..............3/4-14
Straight Metric
Thread Fine .....Male Thread....... Male Thread ......Female Thread..... Female Thread
....................... O.D. mm ............O.D. inches ........I.D. mm............... I.D. inches
M12x1.5 ...........12.0................... 0.47................... 10.5 ......................0.41
M14x1.5........... 14.0................... 0.55 ...................12.5 ......................0.49
M16x1.5 ...........16.0 ...................0.63................... 14.50 ....................0.57
M18x1.5 ...........18.0................... 0.71................... 16.5 ......................0.65
M20x1.5 ...........20.0................... 0.78 ...................18.5 ......................0.73
M22x1.5 ...........22.0 ...................0.87................... 20.5 ......................0.81

5. Aluminum Stat-O-Seal washers with molded Buna-N inner seals are much more reliable than the more common steel stat-o-seals. If the rubber portion fails to make contact all around the port, the aluminum will act as a crush washer, providing a reliable metal to metal seal. Use them to seal screws, bolts or plumbing fittings. The Buna-N seal is resistant to petroleum fuels and oils. Pegasus Auto Racing

https://cimg7.ibsrv.net/gimg/www.cor...6198cf9ed7.jpg

Stat-O-Seal Inside Diameters vs. Outside Diameters
ID Size...#6 (0.138")..#10 (3/16")...1/4"..5/16"...3/8"..7/16"..1/2"..9/16"..5/8"...3/4"...7/8"..1.00"
OD Size............ .38".......... .44".. .50".. .60"... .66".. .76"... .88"...1.06"..1.19".1.32"..1.51".1.76" [/FONT]

6. Pipe Plugs.
1/8 inch NPT Drill is 21/64 or 11/32 inch. Aluminum Allen Head 1/8 inch pipe plugs found here. Speedway Motors

7. Tools.
Often a 1/4 inch socket wrench and associated extensions/swivels are better to use in tight places than 3/8 inch sockets. I use a 3/8 inch and 1/4 inch universal (the "U" joint) in the first picture. I have a complete set of metric and SAE sockets in 3/8 inch and 1/4 inch sizes.

The wobble extensions are in second and third pictures and flex ratchet combination wrenches in fourth picture.

You will notice what allows the wobble in the third picture.

There are all sorts of swivels and swivel socket combinations you can get but these four tools/tool sets will get er done assuming you have a good 3/8 inch and 1/4 inch socket wrench and set of metric sockets with 3/8 inch and 1/4 inch adapters.

Oh...ya...you might need a good 1/4 inch and 3/8 inch torque wrench also. I like the ones that trip at your torque setting. And.....a good set of allen and torx T wrenches.
.
https://cimg7.ibsrv.net/gimg/www.cor...300a705d79.jpghttps://cimg2.ibsrv.net/gimg/www.cor...50b0664931.jpghttps://cimg4.ibsrv.net/gimg/www.cor...19bf8c5c7d.jpghttps://cimg7.ibsrv.net/gimg/www.cor...9bba71ad31.jpg

8. New Tools These from Harbour Freight......

a. 1/4 inch drive Torx #40 hardened steel for Plenum and Cam Cover Bolts (just long enough to reach between those two tight runners on the Plenum).

b. 14 inch long combination 1/4 inch and 3/8 inch drive Flex Head Socket wrench strong enough (even using the 1/4 inch end) to remove the hardest to remove Torx Cam Cover Bolts. The 14 inch leverage eliminates the need for a cheater bar on the typical socket wrench.

https://cimg7.ibsrv.net/gimg/www.cor...e0837e9a17.jpg

Last UPDATE of post 4 Nov, 2022

Use of thread Lubricants, Loctite and Sealants
 

Use of thread Lubricants, Loctite and Sealants

1. General Use of Loctite including Permatex.

In General use Red loctite 262 on all bolts except oil pan bolts, plenum bolts or anything you think you might remove a couple times. Use Blue loctite 242 on those items (Except SS Plenum and SS Cam Cover Bolts). Use Permabond A136 or Loctite 518 on Cam Covers. Use Loctite 565 on sensors, switches, fittings. Use anti-zieze on Spark Plugs a d Exhaust Manifold Bolts with Locking Tabs.

a. Permabond A136 or Loctite 518.
Use Permabond A136 very thin coat on surface of cam covers. Do not coat Permabond A136 all the way to the edge of the journals (stay away 1/4 inch). Coat the grooves with Permabond A136 for the two camshaft rubber plugs on each end of each Cam Covers.

https://cimg2.ibsrv.net/gimg/www.cor...aa11b961dc.jpg

b. Permatex on gaskets associated with Oil and Coolant.
There are several opinions on this but I use a very light coat of Permatex 300 Form A Gasket on both surfaces of mating parts of all assemblies in contact with oil or water (water pump, oil pan and oil filter housing assemblies). I always use a thin coat of Permatex on the Oil Pan Drain Plug, Transmission Fill and Drain Plugs and Differential Drain Plug also. This not only helps seal the plugs but also acts as a thread locker (A little less bolt torque with a good sealant). Tighten just tight enough to not leak on all drain plugs.

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2. Use of Anti-Sieze and Gasket Sealants

I will use anti-sieze on stainless steel bolts, spark plugs, and header bolts (Permatex Anti-Sieze 133A). On the transmission (differential and engine) fill & drain plugs and water pump I use Permatex 300 Form-A-Gasket. On Cam Covers and Cam Cover rubber end seals use a thin coat of Permabond A136.

https://cimg6.ibsrv.net/gimg/www.cor...3ea5100d48.jpghttps://cimg5.ibsrv.net/gimg/www.cor...914bf0d3f7.jpghttps://cimg6.ibsrv.net/gimg/www.cor...ede2618148.jpg

3. Bolt Torque Theory

When a sufficient load is applied to a metal or other structural material, it will cause the material to change shape. This change in shape is called deformation. A temporary shape change that is self-reversing after the force is removed, so that the object returns to its original shape, is called elastic deformation. In other words, elastic deformation is a change in shape of a material at low stress that is recoverable after the stress is removed. This type of deformation involves stretching of the bonds, but the atoms do not slip past each other. This applies to head bolts.

When the stress is sufficient to permanently deform the metal, it is called plastic deformation. This applies to camshaft sprocket bolts.

Now having said that.....what is the relationship between bolt torque, thread lubrication, and bolt tension?

The preload on a bolt, when determined via the torque method, can be off by as much as 25% even with proper precautions being taken especially between lubricated and dry bolt threads.

The purpose of bolt thread lubrication is to ensure that the applied torque deforms the bolt along its axis (stretch) instead of around its diameter (twist).

I have seen a statement that the standard for thread lubrication is a light coat of oil of about 10W viscosity. A thin coat of most engine oils does just fine. The idea is to allow the threads to move against one another and light oil does that reliably. Of course, this standard assumes that the threads of the bolt and nut, or case, or whatever, have reasonably smooth finishes. Exotic or extreme-pressure lubricants such as gear oils or moly pastes are mostly a waste of time and can actually be harmful if they reduce friction too much.

I on the other hand for oil pan bolts and other bolts on engine components such as the water pump, front engine cover (especially threaded into aluminum) use blue thread locker which by itself is a bolt lubricant. I clean and dry the bolt hole and bolt threads (I use a fine wire wheel on bolt threads including head bolts) with gasoline on a que tip for example cleaning out debree and oil films as much as possible. This applies to head bolt threaded holes as well.

You can reuse head bolts but I prefer to use new head bolts since I have no clue how they were first installed. It also depends on how hard they were to remove.

4. The use of Stainless Steel Bolts

There are only a few of us that use stainless bolts (and then only on cam covers and plenum). On the plenum if they are stainless bolts, I expect to be taking that off more often than not anyway. Prolly same with cam covers stainless bolts but less often.

On Cam Covers and Injector Housing Coolant Manifolds when SS Bolts are used I now use no loctite and no Antisieze using the Aluminum Stat-O-Seal washers. The Stat-O-Seal Aluminum washers with molded Buna-N inner seals are much more reliable than the more common steel stat-o-seals. The Stat-O-Seal Aluminum Washers act as a bolt sealing and locking mechanism. I use no Loctite or Antiseize on the Plenum SS bolts as the Plenum may be removed from time to time.

5. Use of Stat-O-Seal Washers

Using Aluminum Stat-O-Seal Washers..........if the rubber portion fails to make contact all around the port, the aluminum will act as a crush washer, providing a reliable metal to metal seal. Use them to seal screws, bolts or plumbing fittings. The Buna-N seal is resistant to petroleum fuels and oils. Pegasus Auto Racing

https://cimg7.ibsrv.net/gimg/www.cor...6198cf9ed7.jpg

6. Thread Galling and Corrosion

Thread galling seems to be the most prevalent with fasteners made of stainless steel, aluminum, titanium, and other alloys which self-generate an oxide surface film for corrosion protection. During fastener tightening (and loosening), as pressure builds between the contacting and sliding thread surfaces, protective oxides are broken, possibly wiped off, and interface metal high points shear or lock together. This cumulative clogging-shearing-locking action causes increasing adhesion. In the extreme, galling leads to seizing - the actual freezing together of the threads".

The basic corrosion resistance of stainless steel occurs because of its ability to form a protective coating on the metal surface. This coating is a "passive" film which resists further "oxidation" or rusting. The formation of this film is instantaneous in an oxidizing atmosphere such as air, water, or other fluids that contain oxygen. Unlike aluminum or silver this passive film is invisible in stainless steel. It's created when oxygen combines with the chrome in the stainless to form chrome oxide which is more commonly called "ceramic".

7. Summary of 262, 242 Loctite, and Permabond A136.

Red loctite 262 on all (non stainless steel) bolts except oil pan bolts, plenum bolts, water pump bolts or anything you think you might remove a couple times. Blue loctite 242 on those items (Except SS Plenum and SS Cam Cover Bolts). Loctite 565 on sensors, switches, fittings.

LOCTITE 262 is designed for the permanent locking and sealing of threaded fasteners. The product cures when confined in the absence of air between close fitting metal surfaces and prevents loosening and leakage from shock and vibration. Typical applications include the locking and sealing of large bolts and studs (up to M25 ). The thixotropic nature of LOCTITE 262 reduces the migration of liquid product after application to the substrate.

LOCTITE 242 is designed for the locking and sealing ofthreaded fasteners which require normal disassembly with standard hand tools. The product cures when confined in the absence of air between close fitting metal surfaces and prevents loosening and leakage from shock and vibration. Suitable for applications on less active substrates such as plated surfaces, where disassembly with hand tools is required for servicing.

LOCTITE 565 is designed for the locking and sealing of metal pipes and fittings. The product cures when confined in the absence of air between close fitting metal surfaces and prevents loosening and leakage from shock and vibration.

Permabond A136 is designed for the Cam Covers and Cam Cover rubber plugs on each end. Permabond A136 from Jerry's

https://cimg8.ibsrv.net/gimg/www.cor...72fe8c656e.jpghttps://cimg9.ibsrv.net/gimg/www.cor...923e57963b.jpghttps://cimg2.ibsrv.net/gimg/www.cor...aa11b961dc.jpg

Last UPDATE of post 5 Aug, 2017

Service Manual Supplement, Secondary Diagnostics. Sensors, and Prom Codes
 

Service Manual Supplement, Secondary Diagnostics, Sensors and Prom Codes

1. Service Manual Supplement.
This Service Manual Supplement is limited to detail LT5 engine pictures, bolt torque, Sealant recommendation, and sequence of disassembly and assembly engine only. No electrical, diagnostics or fault finding (60 pages). Also included is Oil capacity, Engine Specifications, and Special Tools.

https://cimg0.ibsrv.net/gimg/www.cor...d22f8bfbec.jpg

2. Checking Injector Resistance without removing Plenum.
I checked my primary injector resistances without removing Plenum. I disconnected my battery and connected Inj-1 fuse side toward front of my 1991 ZR1 through digital ohm meter to ECM connector A (drivers side most left connector) A8, A3, A2, A7, A1, A12, A13, and A18. I was looking for 12.5 to 14 ohms on primary and secondary injectors.

https://cimg1.ibsrv.net/gimg/www.cor...6f753b817b.jpg

3. Checking Secondary Operation without removing Plenum.
Check Secondary Operation by grounding pin C17 of ECM with key on. My screw driver is now pointing at the location of pin C17 on the ECM (that wire is pink with black strip on my 1991).

https://cimg2.ibsrv.net/gimg/www.cor...98bd2468b5.jpg

4. ZR1 Sensors.
https://cimg4.ibsrv.net/gimg/www.cor...09f6eb3c44.jpg

5. ZR1 Electronic Automatic AC .

The AC parameters can be viewed by pressing and holding the UP and DOWN Fan Buttons untill a -00- appears.
Then press the UP button untill you get to an - 05 (Battery Charge) or a - 16 (Coolant Temperature). Then press center Fan Button to view the Battery Charge (see below) or Coolant Temperature (Deg C). On a Standard 1990 Corvette (L98) the Coolant Temperature is scan UP to - 12 then press center Fan Button.

a. Coolant Temperature.
Coolant Temperature - 16 indicating you are .............Coolant Temperature is 83 deg C or 181.4 deg F
at Coolant Temperature (Now Press Fan)
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b. The Coolant Temperature Calculation Trick.
Deg Centigrade which you observe as 83 deg can be converted to F deg:
(83 x 9/5) +32 = 181.4 deg F

c. Battery Charge.
A bit more complicated for Battery Charge...................Air is OFF in this case
Battery Charge - 05 (Now Press Fan)..........................197 indicating 14.408 volts (see d. below)
https://cimg8.ibsrv.net/gimg/www.cor...f55c6d883e.jpghttps://cimg9.ibsrv.net/gimg/www.cor...7dcab01b37.jpg

Battery Charge - 05 (Now Press Fan)
at Battery Charge -105 indicating 13.742 volts (see B below)
Air is ON in this case

https://cimg0.ibsrv.net/gimg/www.cor...3769b95dd2.jpg

d. The Battery Charge Calculations Tricks
With AC OFF we see 197. The Calculation for a positive number is:
((197/255) x 7 volts) +9 volts = 14.408 volts (the constant is 255 for a positive observed number)

With AC ON we see -105. The Calculation for a negative number is:
(105/155) x 7 volts) +9 volts = 13.742 volts (the constant is 155 for a negative observed number)

6. Prom Code Chart.

https://cimg1.ibsrv.net/gimg/www.cor...9f15983f15.png

Last UPDATE of post 6 Aug, 2017

Thermostats, Fans, Water Pump, and Radiators
 

https://cimg4.ibsrv.net/gimg/www.cor...05bdafb1cc.jpghttps://cimg1.ibsrv.net/gimg/www.cor...ead9daffa4.png

$24......Shows a gasket but came without a gasket....Price was right :thumbs:
Stant 14068 Thermostat

Jerry has the Rubber gasket :thumbs:
Stant 14068 gasket

1. The 180 deg versus the 160 deg thermostat or no thermostat.

We are referring to coolant temperature at the coolant temperature sensor.....

Why not just remove thermostat? NO...NO...NO!!!!

I run 180 deg thermostats in ALL ZR-1s.

A. At a coolant temperature of say 190 deg a 160 deg thermostat is open....so is my 180 deg thermostat. So from that point on our coolant system flow rates are identical at the same rpm. And so is the cooling.
Also see Defective Stant Thermostats

B. Using a 160 deg thermostat in cooler weather drops the engine coolant temperature below the designed engine temperature with the 180 deg thermostat. The PVC (at the cooler engine temperatures) is working at less than optimum temperatures as well as your oil and fuel functioning at less than optimum temperatures.

C. I see no difference between a 160 deg F thermostat and a 180 deg thermostat (both with the same Full Open Head Loss) once the coolant temperature has reached 190 deg F? I know the 190 deg F will be reached slower with a 160 deg F Thermostat but that is the only difference in that you reach the same Coolant Temperature at different rates of temperature increase. Kind of like using light weight pulleys to save HP which HP is only realized on acceleration as the rotational velocity of the pulley changes. Nothing is gained in a constant velocity (constant speed) situation.

FANS Oh....almost forgot.....my fans come on a bit sooner controlled by Marc Haibeck chip to help with engine temperatures when idling at a traffic light on a hot day (On at 205 deg F and Off at 200 deg F). But again....my 180 deg thermostat and the 160 deg thermostat are both open in that condition :D

Unmodified Fan Operation:
Primary Fan On 221-226 deg F (depending on Model Year).
Secondary Fan On 230 -234 deg F (depending on Model Year).

Modified Fan Operation:
Haibeck Chip (Fans On 205 deg F and Off 200 deg F).

2. Thermostat Multiple Functions.

The LT5 thermostat sits in two cavities and is located on the outlet side of the radiator. On one end of the thermostat is the first valve [pressure relief) that expands and opens to excessive radiator pressure (but only relative pressure over and above that normal thermal expansion radiator pressure). That valve is in the first cavity which is exposed to coolant outlet flow. In the second cavity is the second thermostat valve (temperature relief) which controls coolant inlet flow depending on engine temperature.

GM found at high rpm and high coolant flow, excessive pressure in the radiator, due to it's restriction, would blow the rubber seals between the side tanks and the core. GM did not want to design a specific LT5 radiator, so the solution was the radiator bypass which opens when the pressure differential across the radiator reaches a certain level. This bypass valve is part of the thermostat and, when open, allows coolant to recirculate within the engine.

When the Stant Thermostat is Fully Open the bottom end of The Stant Thermostat has two slots equating to approximately .07 square inches opening which feeds coolant back to the engine before passing the radiator. Again, even though the coolant passing through the thermostat from the radiator is of a lower pressure than the coolant passing the bottom of the thermostat before passing through the radiator (Radiator Head Loss), the total opening area of those two slots (.07 square inches) is very small compared to the approximately .75 square inches of a fully open thermostat. The effect of those two slots theoretically is negligible on hindering Engine Coolant passing from the radiator when the Stant Thermostat is Fully Open.

[b]ZR1 provided this photo in the LT5 Coolant System Discussion :thumbs:

https://cimg9.ibsrv.net/gimg/www.cor...a3fc73f8b1.jpg
https://cimg0.ibsrv.net/gimg/www.cor...56ae3e0176.jpg

3. Lets simplify......the discussion of the 160 deg thermostat cooling better than the 180 deg thermostat.

A. Let us say we have identical radiators, identical rpm, steady state coolant temperature, and both fans on and we are cruising at same speed.
B. Lets say coolant temperature is 190 deg in both your Z and my Z given everything identical in item #1.
C. Your 160 deg thermostat is full open with same flow rate as fully open 180 deg thermostat.
D. My 180 deg thermostat is full open with same flow rate as fully open 160 deg thermostat.
E. In other words...we both have been driving our Zs for say at least 30 minutes and have reached a steady coolant state.

Now......lets say the day gets hotter. The coolant temperatures should rise the same in both your Z and my Z given EVERYTHING else is the same :yesnod:

If it gets REAL HOT......both our Zs coolant will reach 230 deg at the same time.

The maximum temperature reached (given it is over 190 deg) will be no different for you than me even though you have a 160 deg thermostat and I have a 180 deg thermostat.

I am saying that my thermostat just maintains a minimum temperature higher than yours.
I am also saying your thermostat does not maintain a lower higher temperature than mine. Once both thermostats are fully open, the coolant temperatures are controlled by everything else mentioned in item #1 and not the thermostats (yours or mine).

4. Fans and Radiators.

Once your fan is on (my fan which may be on at lower temperatures is on).......we have identical radiator cooling no matter how hot it gets outside. The exception is Replacing the Fans with Higher Flow Rate After Market Fans which would solve the ZR-1 Over Heating Issue in Traffic on a Hot Day as long as you keep the rpms above 2,000 rpm(see item #6 below).

Now if we change radiators.....you run stock radiator and I run Ron Davis....DIFFERENT STORY as I have greater dissipation of heat than you at all rpms (water pump speed dependent) and ZR-1 speeds (air flow dependent).

5. Engine RPM.

My experience in all ambient temperatures.

A. In sixth gear running 65 mph (less than 2,000 rpm) the Coolant always gets a bit over 200 deg F. On Hot days the coolant will get a bit over 213 deg F. The key is the Water Pump is not pushing enough flow through the fully open thermostat to cool the engine to a Temperature where the Thermostat takes over (180 deg F).

B. If I shift to 5th gear at 65 mph (more than 2,000 rpm) the coolant temperature drops to Thermostat control (180 deg F) on cool days and drops to near 200 deg F on Hot days.

https://cimg1.ibsrv.net/gimg/www.cor...ead9daffa4.png

My findings are simply that the stock water pump is a bit low on coolant flow rate at rpms under 2,000 rpm. As you can see there is a big jump in Coolant Pump Flow rate between 1,000 rpm and 2,000 rpm and it is in this area or engine RPM that the Coolant Flow Rate is not sufficient in HOT Climates when the ZR-1 is moving in 6th gear at 65 mph.

The overheating issue when idling at a stop sign on HOT days (100 deg +) is more related to Fan Air Flow.
Tests at 50 deg F ambient.
Going 65 mph in 6th (1500 rpm) coolant temperature 205 deg F.
Going 65 mph in 5th (2200 rpm) coolant temperature 192 deg F.
Idling at 750 rpm coolant temperature 204 deg F.
Engine rpm 2000 rpm (not moving) coolant temperature rose to 213 deg F.

So...….At 65 mph it is the coolant flow. At 0 mph (Not moving with rpm at 2,000) it is the air flow.

If I could get the air flow higher while in traffic the issue would then be the coolant flow again where keeping rpm above 2,000 rpm would solve the High coolant temperatures on hot days in traffic.
The Coolant Pump Flow at 800 rpm is 15 gpm. The Coolant Pump actually gets more efficient as the rpm increases from idle to 2,000 rpm.
As Per Marc Haibeck graph provided to the ZR-1 Net email list by Graham Behan about ten years ago, the Coolant Pump flow rate through the engine (not the radiator or thermostat) is:
15 gpm at 800 rpm
18 gpm at 1,000 rpm,
44 gpm at 2,000 rpm,
65 gpm at 3,000 rpm,
90 gpm at 4.000 rpm,
120 gpm at 5,000 rpm at which time cavitation is starting.

The Block Resistance at 100 gpm was 20 psi during these tests which varies as the flow rate of the pump increases. The pressure on the output of the pump during the test was 3 psi at 2000 rpm, ramping up to 25 psi at 5000 rpm. As cited above, the hoses, radiator and bypass valve were not connected as a system as per Marc Haibeck Testing.
The Dual Thermostat Bypass pressure is apparently 5 psi and block resistance at 100 gpm is approximately 20 psi. I am not sure what the radiator Head Loss is at various flow rates but definitely depends on the radiator type which was not part of these tests.
It would seem that the Coolant Pressure Relief Cap on top of the Coolant Reservoir in front of passenger side set at 15 psi would assure the radiator maximum pressure would be 15 psi plus the Bypass Pressure of 5 psi or 20 psi.

6. Summary .....See LT5 Cooling and Radiators TIPS

A. Fans turn on at 205 deg F and OFF at 200 deg F (Haibeck Chip)
B. I use 180 deg Thermostats.
C. Ron Davis, Dewitt, and Fluidyne multi core Aluminum Radiators.
D. To solve the Hot Coolant flow when stalled in traffic would require Fans with Greater Air Flow.

The Thermostat is fully open at all coolant temperatures over 180 deg F (no need to use cooler thermostat unless you want to run at temperatures below 180 deg F).

The Water Pump does not provide enough flow to cool the engine at rpms less than 2,000 rpm. This is not an issue at ambient environmental temperatures on cool days. This is a problem on HOT days. The Aluminum Multi Core Radiators DO provide better Heat Dissipation and offer cooler Coolant at ALL Temperatures for which the 180 deg F Thermostat Controls the Flow (above 185 deg F Coolant temperatures the Thermostat is fully open). The Cooling effects then being dependent on Water Pump Flow Rate and Air Flow Rate through the Radiator.

Having the Fans come on at 205 deg F DOES provide for COOLER Coolant in the radiator once sufficient coolant flow rate is provided above 2,000 rpm. Using Aluminum Multi Core Radiators ALSO provides for COOLER Coolant Temperatures in conjunction with the Air Flow provided by Fans and Vehicle Speed. The Heat Removal Rate from the Radiator is greater as the Air Flow Increases and as the Aluminum exposed to that Air Movement increases.

It DOES make a difference if you are moving at speed in conjunction with Fans PULLING Air Flow as the additional Air Pressure Up Front does add to the TOTAL AIR FLOW through the Radiator at any ambient environmental temperatures.

Using 180 deg Thermostats insures that the engine will not run cooler than that temperature since the Thermostat is in control and controls the Coolant flow rate through the engine at all Coolant Temperatures less than 180 deg F.

7. Modifying the Stant Thermostat.

There has been some suggestions to drill 1/8 inch holes in the thermostat flange to allow better cooling.
Just tested several 180 deg F Thermostats for opening temperatures and found the Stants 180 deg Thermostat will start opening at 175 deg F with complete opening at 185 deg F. Marc suggested at one time the older Stants will deteriorate (Decrease in FUll Open Area) by up to 15% as they age. A thermostat with over 50k miles generally opens 5 degrees later and opens about 85%.

The Stants tested would be fully open with a flow area of approximately .785 square inches at 185 deg F.

Thermostat opening at 175 deg F....................................Thermostat opening at 185 deg F (Full Open)

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A 1/8 inch diameter hole in the flange will offer additional flow area of .0123 square inches. Which one such hole will increase the total flow area by .016 or 1.6% (three 1/8 inch diameter holes would increase the flow area by 4.7%). This thinking does not address the change in coefficient of Discharge of such small holes.

Now compared to the normal aging of the thermostat of 15% over several years of use one would be much better off installing a NEW Stant Thermostat gaining 15% flow area as compared to drilling three 1/8 inch holes in an older Stant Thermostat only gaining 4.7% flow area.

Given the LT5 runs Hotter idling at a stop sign than at 2,000 rpm as cited in Item #5 in the link above a much better focus regarding engine Heating would be engine RPM (which relates directly to pressure on the coolant flow through the Stant Thermostat) and not the Stant Thermostat (Old or New).

8. The Thermostat housing and Heater Hose Connections.

Heater Hose Connection on Thermostat Housing

See Item #2 Replacing the Heater Core and Heater Hose Connection

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Some Thoughts regarding the Thermostat Housing:

A. It does not make any difference if you use a 160 deg thermostat or 180 deg thermostat....they both are fully open at 185 deg.
B. I makes no difference if you drill small 1/8" holes in the thermostat flange as the additional area is only 1.5% increase per hole.
C. The Heater Circuit is open at all times even on a cool engine after start as the heater will be the first to get warm coolant.
D. On a very cold day with the heater on and Interior Fans set at Ten, the Heater Core with significant coolant flow could cool the engine for a significant amount of time before the main temperature controlled end of the Thermostat on the radiator side opens. The engine coolant mixed with some air would still expand into the radiator and to the coolant over flow below the passenger headlight.
E. If you want to cool your engine below the temperature controlled thermostat on a cold day or cool your engine a bit more on a very hot day, run your Heater with Interior Fans set at Ten using Outside Air (not recirculate) with windows open. The additional Coolant Flow through the Heater could be as high as 14% of the total coolant flow with 3/8 inch ID Heater Hoses.
F. The bottom of the thermostat on engine side opens at differential pressure of 5psi when open 1/2 inch allowing coolant to bypass the radiator (Marc Haibeck Testing).
G. When the thermostat has not reached opening temperature (175 deg) the coolant recirculates through the bottom of the thermostat at a pressure of 5psi since the coolant flow through the radiator is blocked.
H. Always use original green coolant GM 1825M.

9. Filling with Coolant.

I fill with Coolant/Distilled Water. Then the BIG Secret......
A. I use a vice grips and close off the coolant to the Plastic Overflow under Passenger Headlight.
B. I fill Black Coolant Reservoir in front of passenger side window and when the bubbling stops.....Blow into/pressurize that Reservoir holding pressure for about 10 seconds. More bubbles will come from the top of the radiator hose. I refill with Distilled Water and Blow into/pressurize the Coolant System again. I repeat this maybe three times until no bubbles come back from the top of the Radiator. I then replace the Coolant Reservoir Cap and remove Vice Grips.....and fire up the LT5 keeping a hand on the Injector Housing Coolant Manifolds to assure they get warm within a minute. (That Happens with this method of Coolant Filling 100% of the time).

With this procedure you are pressurizing both sides of the radiator but with each pressurizing cycle more coolant is being pushed into the coolant system and more air is bubbling out from the top of the radiator.

See Item #7 Blocking TB Coolant, Fluidyne Radiator and Thermostats

Last UPDATE of post 7 April, 2024

LT5 Radiator and Initial Coolant Fill Tricks
 

LT5 Radiator and Initial Coolant Fill Tricks

1. Ron Davis Radiator w/o transmission cooling

Coolant temperature stays at a constant 185 deg (70 deg F ambient) with 180 deg thermostat.*
a. 1989-1996 C4 Type V8 All Part No. 1-16CV8996
b. Rated 800 Hp
c. Manual transmission

* Coolant Temperatures will climb a bit with AC on (100 deg F ambient).

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d. For the Ron Davis radiator the fan shroud inside baffles have to be cut back 5/8 inch so there is not contact with the fins of the radiator. Use a small cut off grinder for that task.
e. I cut the tab on the passenger side of the fiberglass radiator housing (the single tab with larger bolt hole that interferes the most with the oil cooler hoses). The fiberglass radiator housing then slipped on easily without further modifications.
f. Use a Radiator Comb to straighten out any bent fins.
g. Replaced Ron Davis Radiator Nylon Drain Plug with new radiator drain Brass JIC fitting with cap.

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2. When installing SAMCO hoses, set the clamps so the screws are excessable after everything else is installed.
a. The bottom hose clamp screw on the water pump facing down so it can be reached from underneath with a long flat head screw driver.
b. That lower clamp (water pump) has to also be positioned so the screw part does not interfere with the belt tensioner.
c. The top main hose clamp between water pump and thermostat housing (Top) clamp screw facing to rear of engine.
d. This allows you to use a 7 mm box wrench to tighten the hose clamp from above. Make sure this TOP main Water Pump Hose does not touch the Oil Cooler Lines between the Oil Cooler and Oil Filter Housing.
e. Installing SAMCO hoses is kind of tough. I always used bit of Permatex on the hose fittings and in this case coated the inside of the hose a bit with Permatex also which helped start the hose on the various fittings. Trouble is that using Permatex makes the slip on easy but also slip off easy under pressure. So...USE NOTHING ON SAMCO HOSE.
f. I also use a bit of permatex gasket sealer on all mating surfaces (including those with gaskets) having to do with coolant (water pump, thermostat housing, all coolant hoses, and injector housing water manifolds).......no coolant leaks.
g. Use ONLY the SAMCO Hose Clamps with rounded edges that DO NOT cut into the SAMCO Hose when tightened.
h. Install all hose clamps on SAMCO hose as close to the receiving coolant pipe hose clamp retaining ring as possible. The hose clamp retaining ring is the larger diameter ring on all receiving coolant pipes.

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3. Filling with coolant Tricks
See (Filling With Coolant and the Air Locked Water Pump) for Detailed New Coolant Filling Trick.

See LT5 Air Locked Water Pump Simplified for the Simplified Discussion regarding The Air Locked Water Pump.

Note: Getting the Air Out of the Water Pump after Blocking TB Coolant.

A. Disconnect the Drivers side Injector Housing Coolant Manifold "L" from the Drivers side Injector Housing Coolant Manifold and rotate that "L" up connected to the Drivers side Coolant Crossover Pipe.

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Attach a second "L" to the Injector Housing Coolant Manifold rotated up and fill that "L" with coolant. Blow into that "L" forcing coolant into the water pump through the Drivers side Injector Housing Coolant Manifold (Only blow in steps refilling the "L" with coolant each blow effort). You can see in the photo that by blowing coolant into the Drivers Side of the water pump air will be forced out to the top level of the impeller with only a small amount of air left on the passenger side of the water pump.

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B. Refill the Drivers Side "L" temporarily connected to the Drivers Side Coolant Manifold with coolant and do that trick a couple times until the coolant flows out of the Drivers Side Crossover "L" that has been rotated up.

When you blow (force) coolant into Port A of the Water Pump (Blowing in steps) you replace the yellow area of Air with Water. The Air is forced out the top and down left side through Port B. (Only blow in steps refilling the "L" with coolant each blow effort).

Do NOT rely on the temperature gauge to tell you if the Water Pump is functioning. If the two Injector Housing Coolant Manifolds are NOT getting warm rather quickly (within 1 minute), your coolant is NOT flowing.

4. The Simplified Method........I fill with Coolant/Distilled Water. Then the BIG Secret......
A. I use a vice grips and close off the coolant to the Plastic Overflow under Passenger Headlight.
B. I fill Black Coolant Reservoir in front of passenger side window and when the bubbling stops.....Blow into/pressurize that Reservoir holding pressure for about 10 seconds. More bubbles will come from the top of the radiator hose. I refill with Distilled Water and Blow into/pressurize the Coolant System again. I repeat this maybe three times until no bubbles come back from the top of the Radiator. I then replace the Coolant Reservoir Cap and remove Vice Grips.....and fire up the LT5 keeping a hand on the Injector Housing Coolant Manifolds to assure they get warm within a minute. (That Happens with this method of Coolant Filling 100% of the time).

With this procedure you are pressurizing both sides of the radiator but with each pressurizing cycle more coolant is being pushed into the coolant system and more air is bubbling out from the top of the radiator.


5. Coolant Overflow Under Passenger Side Headlight.
When the engine is Hot I fill the Coolant Overflow reservoir to within an inch of the top. On a Hot Engine the coolant overflow is filled by the expanding hot coolant to its maximum fill. As the engine cools the coolant is then sucked back into the engine.

What happens after doing some coolant draining during Plenum Pull or thermostat installations, is the engine develops Air Pockets in the coolant system. As the engine warms up to Hot these Air Pockets are pushed out of the engine into the Coolant Overflow. Once the Air gets into the Coolant Overflow the air is caught at the top of the coolant never to return to the engine (Which is exactly the purpose of the Coolant Overflow).

All the Air caught within the engine is flushed out by the Water Pump as you rev the engine once the engine has reached optimum temperature. The Air ends up within the Top Side of the Radiator where that Air is pushed out of the radiator into the top of the Black Coolant Reservoir in front of the Passenger Side Windshield. From their the air is forced into the Coolant Overflow as the Hot Air and Hot Coolant expands during engine Warm Up to Engine Hot.

If after several cycles of Engine Operation the Coolant Overflow continues to loose Coolant, You Have a Coolant Leak in your System.

Last UPDATE of post 8 Aug, 2017

HVAC Temperature Display And Radiator Efficiency Test Runs
 

HVAC Temperature Display And Radiator Efficiency Test Runs


1. Using HVAC Display for Engine Coolant Temperature.
This post applies to both C4 (L98) and (LT5) engines.

ghlkal brought my attention to this great tip :thumbs:

Using the HVAC Display parameter #16 digital readout for continous Engine Coolant Temperature in deg C where deg F=((9/5)(deg C) +32) can be accomplished by pressing the two Fan Buttons.

Press both Fan Up and Fan Down together waiting 3 seconds to enter HVAC diagnostics. Then press Fan Up to parameter #16 and then press Auto (between the two Fan Buttons) to read the Engine Coolant Temperature in deg C which Engine Coolant Temperature will be a real time continous reading.

The Engine Coolant Temperature is exhibited in real time continuously untill you exit the HVAC diagnostics or select another parameter by pressing Fan Up or Fan Down (engine running or not and idling in neutral or driving down the road). I shoot for 94 deg C to 104 deg C (200 deg F to 220 deg F) on a hot 100 deg F day at highway speeds with AC set at 72 deg (using a 180 deg thermostat and Fans On 205 deg F Fans Off 200 deg F with Marc Haibeck Chip ).

You can now compare Engine Coolant Temperature gauge reading to Engine Coolant Temperature HVAC digital read out. You can compare as a check of the Engine Coolant temperature gauge and two separate Coolant Temperature Sensors located essentially in the same area of the engine (drivers side inside IH under Plenum).

The Temperature Sensor (two pin connector) that controls the cooling fans also provides the information for the HVAC digital readout. The Temperature Gauge is controled by the adjacent Temperature Sensor (button terminal).

Photo provided by Jerry of Jerry's Gaskets.

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2. Effectiveness of LT5 Radiators/Cooling Fan Systems.

The Bottom Line Question for any discussion regarding Effectiveness of LT5 Radiators/Cooling Fan Systems is How do the Radiator/Fans Cool the LT5 Engine with AC On at 100 deg F Ambient Temperatures while idling in traffic.

Let us assume for simplicity that LT5 engine cooling is about the Radiator Air Flow and Radiator Coolant flow (as 5ABI VT and Goldcylon suggests). Lets further assume that the engine sensors, heat generation, spark advance, compression, load are identical between engines at a certain engine speed and ZR-1 speed in other words nothing to consider other than the air flow, coolant flow, and coolant temperature from the HVAC Display (AC ON and AC OFF).

I am going to do some testing to verify exactly how two ZR-1s here in CA (90' with stock radiator and 91' with Ron Davis radiator) behave at 100 deg ambient temperatures (stop and go and on freeway at various speeds). I will determine exactly what the coolant temperatures are at 60 mph and 2,000 engine rpm in 5th Gear (including the worst condition idling with ZR-1 not moving). The Conditions I have are a 180 deg F Thermostat and Fans ON at 205 deg F and OFF at 200 deg F running on 91 Octane Fuel (Marc Haibeck Chip).

I am thinking ALL radiators function well at ambient temperatures around 90 deg F and lower.....it is the 100 deg F ambient temperatures that are of issue.

Using HVAC Display for Engine Coolant Temperature
Water Pump, Coolant Temperatures, and Coolant
Coolant Characteristics (Mix, Pressure, Elevation)

A. Experiment Number 1
1990 Fans On 205 deg F Fans Off 200 deg F
Stock Radiator
100 deg F Ambient
at least 50% Coolant Mix

AC On 72 deg AC Fan 7
Cruise 60 mph 5th HVAC temp 220 deg F (after exceeding that temperature during the idle test)
(this was interesting because once the temperature came down to 204 deg F with AC Off the temperature did not rise above 205 deg F with AC On)
AC Off 60 mph 5th HVAC temp 204 deg F and dropping slowly
Fans are Controlling Coolant Temperatures when AC is Off

AC On 72 deg AC Fan 7
Idle (not moving) HVAC 235 deg F and climbing (idle for 5 minutes)
Coolant Temperature would keep climbing if I did not turn AC Off within a few minutes

AC Off
Idle (not moving) HVAC 230 deg F and dropping slowly
Coolant Temperature CAN BE CONTROLLED by Turning AC Off

B. Experiment Number 2
1990 Fans On 205 deg F Fans Off 200 deg F
Stock Radiator
90 deg F Ambient
at least 50% Coolant Mix

AC On 72 deg AC Fan 7
Cruise 60 mph 5th HVAC temp 205 deg F

AC On 72 deg AC Fan 7
Idle (not moving) HVAC 228 deg F (idle for 10 minutes)
Coolant Temperature is stable at 228 deg F with AC On with Ambient Temperature 90 deg F

In Summary From this experiment at 100 deg F and 90 deg F Ambient Temperatures the 1990 ZR-1 with stock radiator and Marc Haibeck Chip controlling the fans On at 205 deg F and Off at 200 deg F the following results were obtained.........

1. The Fan thermal switching control the Coolant Temperature (100 deg Ambient) when moving with AC Off (With AC On the Fans are always On).

2. At 100 deg Ambient Temperatures the 180 deg thermostat is not a player staying open under ALL conditions.

3. At 100 deg Ambient Temperatures the Coolant System FAILS when idling in traffic or at stop lights for over 5 minutes with AC On.

4. Excessive Coolant Temperature at Idle with AC On can easily be controlled by turning the AC Off.

5. It also was determined that if the Ambient Temperature dropped to 90 deg F the 1990 ZR-1 can idle in traffic at a stop indefinitely with AC On.

(For those not having the Marc Haibeck Chip the Fan Controlled Coolant Temperatures in this experiment would be 234 deg F).

C. Experiment Number 3
1990 ZR-1 #72 (40,000 miles).
50 deg F - 70 deg F outside Air Temperature.
Ron Davis Radiator.
Haibeck Chip (fans ON 205 deg F, OFF 200 deg F).
Stock Exhaust.
180 deg F Thermostat.
Green Antifreeze down to -10 deg F.

6th Gear
65 mph
1,500 rpm
207 deg F Engine Coolant Temperature

5th Gear
65 mph
2,200 rpm
190 deg F Engine Coolant Temperature

17 deg F cooler running 65 mph in 5th Gear rather than running 65 mph in 6th Gear.
Did the cycle several times with identical results. Coolant Temperatures moved from min to max and back in a minute or two after shifting Gears.

Idle at 850 rpm 203 deg F.

D. Experiment Number 4
1995 ZR-1 #186.
70 deg F outside Air Temperature.
Fluidyne Radiator.
Haibeck Chip (fans ON 205 deg F, OFF 200 deg F).
Stock Exhaust.
180 deg F Thermostat.
Green Antifreeze down to -10 deg F.

6th Gear
65 mph
1,500 rpm
207 deg F Engine Coolant Temperature

5th Gear
65 mph
2,200 rpm
190 deg F Engine Coolant Temperature

17 deg F cooler running 65 mph in 5th Gear rather than running 65 mph in 6th Gear.
Did the cycle several times with identical results. Coolant Temperatures moved from min to max and back in a minute or two after shifting Gears.

Idle at 850 rpm 203 deg F.

Notes:

1. The Water Pump Flow at 800 rpm is 15 gpm. The Water Pump actually gets more efficient as the rpm increases from idle to 2,000 rpm.
As Per Marc Haibeck graph provided to the ZR-1 Net email list by Graham Behan about ten years ago, the water pump flow rate is:
15 gpm at 800 rpm
18 gpm at 1,000 rpm,
44 gpm at 2,000 rpm,
65 gpm at 3,000 rpm,
90 gpm at 4,000 rpm,
120 gpm at 5,000 rpm at which time cavitation is starting.
2. The Dual Thermostat Bypass pressure is apparently 5 psi and block resistance at 100 gpm is approximately 20 psi. I am not sure what the radiator Head Loss is at various flow rates but definitely depends on the radiator type.
3. It would seem that the Coolant Pressure Relief Cap on top of the Coolant Reservoir in front of passenger side set at 15 psi would assure the radiator maximum pressure would be 15 psi plus the Bypass Pressure of 5 psi or 20 psi.

See Post 120 - Thermostats, Fans, Radiators and Coolant Filling

Last UPDATE of post 9 Aug, 2017

Water Pump, Coolant Temperatures, and Coolant
 

Water Pump, Coolant Temperatures, and Coolant

Just when you think you have covered all technical issues. When I say "Water" I am talking about an "engine coolant mix" of your choice (Regular Green Coolant (GM 1825M) or Original Formula (GM 1825M)).

1. Water Pump Failures

a. Failed gasket causing water leaks.
* Water leaks from water pump gasket down on power steering unit or harmonic balancer.
* Water can be found on floor beneath front of engine.

b. Failed water pump bearing.
* Water pump pulley looks crooked.
* Squeeling or other noise from water pump area with engine running.
* Water pump pulley is loose or play can be felt by hand.

c. Water pump impeller spins freely on water pump shaft.
* Engine temp increases considerably.

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2. Installing a Water Pump

It is difficult to install a water pump incorrectly. This water pump had no leaks in gasket and was free spinning by hand immediately after installation as a check. The water pump impeller was firmly attached to the shaft when installed.

If you drop everything on the floor after all that taking account of where the bolts go. Not to worry....

With the water pump in position on the front engine face, just insert the bolt into the water pump housing to the threaded area on the front engine face. Make sure you have about 3/8 inch (or a bit more or less) showing between the bolt head and water pump surface.

As you remove the water pump bolts (during water pump removal) you can confirm that bolt head to water pump surface distance. Some of those "water pump" bolts hold the front cover as well as the water pump to the engine block

All bolts should be about the same in this regard (bolt head to water pump surface distance). If you have more or less space between bolt head and water pump surface as the bolt begins to thread, the bolt is in wrong place.

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I think this was an aftermarket water pump and the Solution to such potential disasters is to buy a new AC Delco water pump.

I use a very thin coat of Permatex 300 Form A Gasket on each side of the Water Pump gasket and IH coolant manifold gaskets before installing. I use a drop of Blue Loctite 242 on all water pump bolts and torque all water pump bolts 18 ft-lbs. NO LEAKS

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3. Coolant Temperatures

Just got back with my 90' L98 climbing Grapevine on I-5 in 110 deg temps. I counted no less than 20 cars/trucks stopped alongside the road with hoods up (you know what that means) ;)

My temps got up to 225 deg F climbing to the top with Air on. With Air off the temps dropped a few degrees. Just as a point of reference I was using HVAC for digital readout.

The radiator in my L98 is stock but in my 91' Z I have a Ron Davis Radiator.

Did some testing yesturday (91' ZR1 with LT5) in stop and go traffic at 105 Deg F (or higher) ambient temperatures....With Air on I approach 110 deg C Coolant Temperatures and with air off back down to 105 deg C. I ended up turning engine off at long stop lights. Cruising 25 mph more or less ....Coolant Temperatures with Air On stayed 105 deg C or less and once on the road cruising at 50 mph Coolant temperatures stayed below 100 deg C. This is with Ron Davis Radiator and Stock Fans coming on at 205 and both off at 200 degs (Marcs Custom Chips work perfectly).

I used HVAC Display to check continous digital Coolant Temperatures.

I would suggest that we have reached the limits of the cooling system and in particular, the limit is air flow through the radiator and around the engine (Fans). I would suggest if one really wanted to solve this issue, install higher flow rate fans. But then again we are talking extremes in Ambient Temperatures (100 deg and above or maybe mid 90s and above).

Since I essentially have the same results running a 90' (L98) and a 91' (LT5) in HOT ambient Temperatures hill climbing as well as in Stop and Go Traffic.......I would suggest a limit in the coolant systems has been reached.

Reaching Limits in Engine Cooling systems was not Abnormal climbing the Grapevine in temps over 105 deg F as many of those cars/trucks parked alongside the road with hoods up were relatively NEW cars and trucks.

4. Marc Haibeck Discussion of Voltage Effects on Engine Cooling

I asked Marc some questions regarding Cooling Fans and Cooling Fans operations with some very interesting facts/Observations presented by Marc. Marc gave me permission to post that information here.....thank you Marc :thumbs:

"The same OE fan is used on all '90 to '94 Corvettes regardless of the engine type. They run at high speed all of the time.

'90 - '92 Primary on at 226 degs. F, off at 216. Secondary on at 234 degs. F, off at 225.
'93 - '95 Primary on at 222 degs. F, off at 212. Secondary on at 230 degs. F, off at 221.
'95 ZR-1 has three fan relays which is different than the earlier years. On the '95 both fans are turned on at half speed at 222 degs. Both fans go on at full speed at 230 degs.

Many other GM cars have the fans wired for high or low speed. The fans are single speed but the relays turn on both fans wired in series for low speed. Then each fan gets power at six volts. For high speed the relays connect direct 12 volts to each fan.

I recently observed that the alternator output plays a significant roll in ZR-1 fan cooling. A typical alternator sets the system voltage between 13.5 and 14.5 volts when the ambient temperature is at about 90 degs. F.

In my opinion the cars with the alternators at the higher end of the normal range at 14.5 volts run a few degrees cooler. With the AC on there is also little more air flow from the interior vents for better AC performance. If fan engine cooling is a problem, consider the system voltage as a factor."

From this I would say also Battery Condition is a factor on maintaining the higher voltage for optimum Radiator Cooling Fans operations.

5. Coolant Selection SUMMARY

You want to only use the green coolant. They have it at Napa and it meets 1825M GM Spec.

For Zerex the first gallon is called Regular Green Coolant (GM 1825M), the second gallon is called Original Formula (GM 1825M). Zerex ZXRU1 is 50-50 and Zerex ZX001 is undiluted. The third gallon is NAPA coolant (GM 1825M).

http://partimages.genpt.com/partimages/213991.jpgORhttp://ecx.images-amazon.com/images/I/31jb-ZubjrL.jpgORhttp://partimages.genpt.com/partimages/213967.jpg

NAPA

5. What is a Failing Coolant System.

85 C (185 deg F) is about when your thermostat is fully open (180 deg thermostat). The 96 C is when your fans prolly come on and 93 C is when your fans prolly turn off (Marc Haibeck Chip). Marc typically has BOTH Fans turn ON at 205 deg F and OFF at 200 deg F.

Now so far your testing at cruising (Outside Air Temperature right around 80 deg F) is not too significant. It is the idling at a stop light for several minutes (Outside Air Temperature 100 deg F) that is the BIG TEST which is FAILED by ALL stock Radiators cooling the LT5 (Especially with AC ON).

This Ambient Air Condition (100 deg F) and operational Condition (idling at a stop light) challenges the Most Efficient Radiators (Ron Davis, Dewitt, and even Fluidyne).

When I say FAILED....I am talking Coolant Temperatures greater than 110 C to 112 C (230 deg F to 234 deg F). It is interesting that the 234 deg F is when both fans come on (Stock Engine).

I am suggesting that Coolant Temperature of 234 deg F is NOT failing when Outside Air Temperatures are 100 deg F and you are idling at a stop light for several minutes.

I am also suggesting that without Marc's chip and with a stock radiator the Coolant Temperatures WILL EXCEED 234 deg F (on a 100 deg F day with AC ON idling at a stop light) which I would say is a failing Coolant System.

Also keep in mind the LT5 operating at less than 2,000 rpm does NOT provide a sufficient coolant flow rate to cool the engine no matter the air flow through the radiator on a HOT day.

See Post 7 - Thermostats, Fans, Water Pump, and Radiators

See Post 120 - Thermostats, Fans, Radiators and Coolant Filling

Last UPDATE of post 10 Aug, 2017

Keeping the L T5 Cool and Radiator Debris Screens
 

Keep the LT5 Cool using a Stant 180 deg F Thermostat and Ron Davis Aluminum Radiator.

See Post 120 - Thermostats, Fans, Radiators and Coolant Filling

Also Clean/straighten all fins on Oil Cooler and AC Condenser :cheers:

180 deg F Thermostat

https://cimg5.ibsrv.net/gimg/www.cor...4209fec76d.png

Ron Davis 1-16CV8996 Aluminum Radiator for 1990/1991 ZR-1s :thumbs:

1989-1996 C4 Type V8 All Part No. 1-16CV8996

-Rated HP: 800*
-Manual transmission
-Core is thicker than factory unit, shroud must be trimmed.

https://cimg8.ibsrv.net/gimg/www.cor...49b29c5d9c.jpghttps://cimg9.ibsrv.net/gimg/www.cor...23b26fe59a.jpg

LT5 Thermostats
LT5 Radiator and Initial Coolant Fill Tricks

To read Digital Coolant Temperatures.....

1. Push and hold up and down (each side of Fan Control button) until you get zeros in display on left.
2. Then push up button to right until you get to 16 in the display.
3. Then push center fan button to read digital coolant temperature in degrees C continually in the display until you hit the temperature button.
80 C is 176 F
85 C is 185 F
90 C is 194 F
95 C is 203 F
100 C is 212 F
105 C is 221 F
110 C is 230 F
115 C is 239 F
120 C is 248 F
125 C is 257 F
130 C is 266 F

Radiator Debris Screens

91' ZR1 (LT5), 90' ZR1 (LT5), and 90' Corvette (L98).

Use 1/8 inch steel pop rivets with washers back side of Air Deflector and on front of screen (approximately 5/16 inch mesh). Drill 1/8 inch holes in the rubberized air deflector. Use cable ties on top side of screen (cable ties not required on 90' Debris Screen installation).

91' ZR1 (LT5) Slot in Debris Screen Required for Air Deflector Brace.
https://cimg6.ibsrv.net/gimg/www.cor...6476b34725.jpg

90' Corvette (L98)
https://cimg7.ibsrv.net/gimg/www.cor...498319cad0.jpg

90' ZR1 (LT5)
https://cimg7.ibsrv.net/gimg/www.cor...c129f890a9.jpg

In the 90' Debris Screen installation you will see a slot in the Air Deflector for the Tow Bar when needed (see item #2 and #3) Lifting and Towing the ZR-1

The 90' Debris Screen (unlike the 91' Debris Screen) does not require a slot for the Air Deflector Brace.

The 91' Air Deflector has also been modified with Tow Bar slot but not shown in above 91' Debris Screen installation.

Last UPDATE of post 11 Aug, 2017

Getting The Air Out of the Coolant System
 

Getting The Air Out of the Coolant System

Eliminating the TB and Plenum coolant flow paths leaves you with this coolant flow shown in the diagram. I would assume water pressure/flow out of each injector housing (equal flow) into the injector housing coolant manifolds would push most of the air out of those manifolds and into the radiator which has a return line to the pressurized coolant expansion tank on passenger side near firewall (which IS the high point in the system).

https://cimg4.ibsrv.net/gimg/www.cor...2801f45bf9.jpg

Getting the air out of the Coolant flow

It is assumed the air gets pushed out of the injector housing coolant manifolds on each side (equally) since they are higher than the radiator coolant line going back to the coolant expansion tank on passenger side (the highest point in the coolant system).

It appears that the water pump pressure and resulting coolant flow into each cylinder block (right and left) would be close to equal since the coolant flow is separated almost equally on the face of the front cover where the water pump is mounted. The exception here is the length of the coolant path from the water pump impeller is longer on Passenger side which could explain a bit higher coolant pressure on Drivers side to assist TB Coolant Flow from Drivers Side to passenger side. There are two holes of equal size that go into the front of each cylinder block (right and left) from the front cover. In other words, the coolant is not pushed from the water pump into a single flow after which the flow is divided but rather the coolant flow is divided at the impeller of the water pump.

https://cimg8.ibsrv.net/gimg/www.cor...53d8362ffc.jpg

If the water pump can pump 100 GPM (385 cubic inches/sec) through two ports (lets assume 1-1/4 inch diameter or 1.23 square inches cross section each port), the coolant velocity would be 156 in/sec or 13 ft/sec in each port. That is intuitively enough flow to prevent a bubble of air going the other way in that flow assuring all air is pushed out of the system.

The Water Pump Flow at 800 rpm is 15 gpm. The Water Pump actually gets more efficient as the rpm increases from idle to 2,000 rpm.
As Per Marc Haibeck graph provided to the ZR-1 Net email list by Graham Behan about ten years ago, the water pump flow rate is:
15 gpm at 800 rpm
18 gpm at 1,000 rpm,
44 gpm at 2,000 rpm,
65 gpm at 3,000 rpm,
90 gpm at 4,000 rpm,
120 gpm at 5,000 rpm at which time cavitation is starting.

It is assumed the water pump is NOT air locked which is the first thing to check for when refilling with coolant. See Filling With Coolant and the Air Locked Water Pump

A Simplified Method.......I fill with Coolant/Distilled Water. Then the BIG Secret......
A. I use a vice grips and close off the coolant to the Plastic Overflow under Passenger Headlight.
B. I fill Black Coolant Reservoir in front of passenger side window and when the bubbling stops.....Blow into/pressurize that Reservoir holding pressure for about 10 seconds. More bubbles will come from the top of the radiator hose. I refill with Distilled Water and Blow into/pressurize the Coolant System again. I repeat this maybe three times until no bubbles come back from the top of the Radiator. I then replace the Coolant Reservoir Cap and remove Vice Grips.....and fire up the LT5 keeping a hand on the Injector Housing Coolant Manifolds to assure they get warm within a minute. (That Happens with this method of Coolant Filling 100% of the time).

With this procedure you are pressurizing both sides of the radiator but with each pressurizing cycle more coolant is being pushed into the coolant system and more air is bubbling out from the top of the radiator.

Thermostat bypass

The radiator Bypass Hose (see above coolant flow diagram) contains the hot coolant coming from the passenger side injector housing as stated below in red. The other companion hose (Radiator Inlet Hose) coming from the drivers side injector housings goes to the top (return line) of the radiator.

Both hoses are connected together at the top front of engine so the coolant flow from each injector housing may comingle with either the radiator bypass or radiator inlet.

https://cimg3.ibsrv.net/gimg/www.cor...8d4a5c6d6c.jpg

Coolant refilling........See LT5 Radiator and Initial Coolant Fill Tricks

Coolant Overflow Under Passenger Side Headlight.
When the engine is Hot I fill the Coolant Overflow reservoir to within an inch of the top. On a Hot Engine the coolant overflow is filled by the expanding hot coolant to its maximum fill. As the engine cools the coolant is then sucked back into the engine.

What happens after doing some coolant draining during Plenum Pull or thermostat installations, is the engine develops Air Pockets in the coolant system. As the engine warms up to Hot these Air Pockets are pushed out of the engine into the Coolant Overflow. Once the Air gets into the Coolant Overflow the air is caught at the top of the coolant never to return to the engine (Which is exactly the purpose of the Coolant Overflow).

All the Air caught within the engine is flushed out by the Water Pump as you rev the engine once the engine has reached optimum temperature. The Air ends up within the Top Side of the Radiator where that Air is pushed out of the radiator into the top of the Black Coolant Reservoir in front of the Passenger Side Windshield. From their the air is forced into the Coolant Overflow as the Hot Air and Hot Coolant expands during engine Warm Up to Engine Hot.

If after several cycles of Engine Operation the Coolant Overflow continues to loose Coolant, You Have a Coolant Leak in your System.

Last UPDATE of post 12 Aug, 2017

TB Coolant Discussion
 

TB Coolant Discussion

Some guys who swear by the fact that TB coolant flow keeps the TB warm and prevents icing are missing some key technical issues me thinks :D

Explanation

1. The TB Coolant is not a flowing system once the engine is heated up. The TB coolant on passenger side connects to a "T" back to the pressurized overflow tank just in front of the passenger under the hood (highest point in the system). The "T" is in the line from the air vent/heat expansion path from the top passenger side of radiator. That radiator vent/heat expansion path is also NOT flowing once the engine heats up. The TB Coolant Design is in regard to VENTING Air and not TB heating and then only during initial engine heating up (And then only if you have a lot of air in your coolant system after opening up your coolant system for repairs or leaks such as coolant leak repair or Plenum/IH Housing, Head removal or Water Pump/Thermostat/Radiator repair).

2. The TB coolant and top side of radiator vent back to the pressurized expansion tank (High point in coolant system) receive air/coolant as the engine is heated up and coolant/air in the system expands.

3. As coolant/air expands (as engine is heated up) the excess air/coolant overflows through the pressurized radiator cap in that high point pressurized expansion tank to the coolant reservoir under the passenger side headlight.

4. The purpose of that system is to allow coolant/air to move back and forth between the coolant expansion tank and coolant reservoir as coolant/air expands during engine heats up/cools down purging the system of air. This occurs by the fact once the coolant system air is forced out the pressurized radiator cap to coolant reservoir, only coolant returns from the reservoir as the coolant system retracts while engine cools once turned off (assuming you have proper coolant levels in the overflow tank under the passenger side head light).

5. Now back to TB coolant.............There is no coolant/air flow between the top side of radiator or TB to the coolant expansion tank on passenger side (high point in system) once the engine is heated up. A CAVEAT would be the small coolant head loss in the IH manifolds to the top side of radiator which would be equalized by a identical small coolant head loss of any flow through the TB and back to the top side of radiator via the coolant expansion tank (a very small diameter line and a very small coolant flow rate).

6. It appears to me that the only reasons for TB coolant (when there is movement of coolant/air between top side of radiator, TB, and expansion tank) is:
A. To warm up the TB QUICKER during engine initial heat up and to move coolant/air from the IH housing coolant manifolds back the coolant expansion tank quicker. This all happens when you first start the engine up when the thermostat is closed and radiator circulation is stagnant.
B. To prevent icing of the Throttle Body when temperatures are below approximately 10 deg F.

7. In other words, with the LT5 coolant system at first start up with a cold engine the coolant is recirculated entirely in the engine and not through the radiator. The TB coolant as the engine coolant expands then allows coolant/air a path back to the coolant expansion tank when there is no return of that expansion from the radiator since the radiator is cold and not functioning yet.

8. Once the thermostat opens up the radiator coolant expansion occurs as the radiator heats up pushing more air from the top side of the radiator to the expansion tank. So if you block the TB coolant you do not let the air out during initial engine coolant heating but that is not an issue if you do in fact have most of the air out of the system during initial coolant fill. Coolant/air can expand through the radiator even though the thermostat is closed however as the engine heats up.

9. The coolant system air has a second chance to excape to the expansion tank during radiator coolant/air expansion once the thermostate opens up allowing hot coolant to flow through the radiator.

10. Throttle Body Coolant Line Blocked
https://cimg4.ibsrv.net/gimg/www.cor...88c37c2687.jpg

A. You can Block TB Coolant at Injector Housing.
You can Block TB Coolant at Injector Housing without removing Injector Housings.
Recommend removing Two Injector Housing Coolant Manifolds to Block TB Coolant at Injector Housings.
You can then keep or eliminate the Plenum hoses/tube on passenger side or leave it in place.
No more hose clamps required on the TB Coolant Hoses to TB if you want to leave the stock look.
You do have to Block TB Coolant near Coolant Reservoir if you Block TB Coolant at Injector Housing.
B. You can also Bypass TB Coolant with the Coolant circulating through the Injector Housing/Plenum.

1991 LT5 with TB Coolant Blocked at Injector housing,
ALL TB Coolant Hoses and Tube eliminated using 1/8 inch Allen Pipe Plugs
https://cimg6.ibsrv.net/gimg/www.cor...0b2f5f80bf.jpg

1990 LT5 with TB Coolant Blocked at Injector housing, ALL TB Coolant Hoses
and Tube In Place
https://cimg8.ibsrv.net/gimg/www.cor...f24e77caff.jpg

Last UPDATE of post 13 Aug, 2017

Coolant Characteristics (Mix, Pressure, Elevation)
 

Coolant Characteristics (Mix, Pressure, Elevation)

High Coolant Temperatures have happened before........stay out of slow traffic in hot weather for long periods of time especially climbing steep hills.

Check for coolant in the oil (coolant will sit at the bottom of oil pan). Check for oil in the coolant (oil will float on top of the coolant in the coolant reservoir in front of passenger side). If your oil level seems to be increasing or decreasing or your coolant level decreasing abnormally that is another indicator. You are checking for a failed Head Gasket.

Do a compression test once in a while to make sure nothing is going on with head gasket, valves, rings.

Then sit back and drive up that hill keeping the speed up to at least 20 mph....40 mph preferred........you NEED some dynamic air flow around the radiator :cheers:

If you continue to do this......definitley turn on your fans at lower coolant temperatures and Turn your AC off at those high temps when climbing that hill (better for you to suffer than your engine) :D

Stock Fan Control on ZR-1s
'90 - '92 Primary fan on at 226 degs. F, off at 216 degs. Secondary Fan on at 234 degs. F, off at 225 degs.

Marc's chips turn Cooling Fans on at 205 deg and off at 200 deg. Those Chips will give you a few minutes more of cooling you do not have with a stock chip maybe enough time to get you to the top of the hill :D

Custom Engine Calibrations
LT5 Performance Engine Calibrations

I expect you will have NO issues unless you have run with loss of coolant such that you were circulating air entrained coolant. Or coolant mix was such that those temperatures caused coolant to boil off which you would notice in your coolant overflow tank under right headlight :thumbs:

This from a Google Search for Specifics on Boiling Characteristics of Coolant
The pressure cap on a cooling system is the key to raising the boiling point of the 50/50 mix of antifreeze and distilled water. For every pound of pressure cap rating the boiling of point of the above mixture raises 3 degrees. If you had plain water in your cooling system with a 15 pound pressure cap the water would boil @ 257 degrees. If you had a 50/50 mix of antifreeze and water the coolant would boil @ 265 degrees with a 15 pound cap. The boiling point would raise to 270 degrees if you had a 60% antifreeze mixture with a 15 pound cap. If you had a 70% mixture the boiling point would raise to 276 degrees.

Don't be fooled by the old wives tail that by adding a richer antifreeze mixture will keep the complete system cooler. In fact it works just the opposite. As you know pure antifreeze has a higher viscosity rating than plain distilled water. The higher the antifreeze mixture percentage its ability to adsorb heat from the engine goes down. The higher the antifreeze mixture percentage also retards the radiator's ability to get rid of the coolant heat.

Race cars use pure water in their cooling systems because it adsorbs heat from the engine and gets rid if it in the radiator better than any antifreeze mixture.

It's to your cooling systems advantage to mix your pure antifreeze/water mixture to protect the engine from freezeing 10 degrees lower than last years coldest day last winter.

Pure antifreeze boils @ 387 degrees Farenheit in atmosphere.

I also happen to know you are at high elevations ;)

This from a Google Search on Specifics on the Boiling Characteristics of Coolant Related to Elevation
With NO pressure cap......Water boils at 212 degrees at sea level. Water boils at 204 degrees at 4,000 feet elevation. Water boiled at 192 degres at 9,000 feet elevation. A 50/50 mixture of water to anti freeze will boil at 227 degrees at sea level. A 50/50 mixture of water to anti freeze will boil at 220 degrees at 4,000 feet elevation. A 50/50 mixture of water to anti freeze will boil at 212 degrees at 9,000 feet elevation. The anti freeze referred to here is ethylene glycol based. Both of these are with no pressure cap on the radiator. You can add 7 degrees to the boling point with the addition of each 1lb of pressure on the pressure cap.

Last UPDATE of post 14 Aug, 2017

Lifting The LT5
 

Lifting The LT5

1. Engine Lift
a. Harbor Freight 2 Ton Engine Lift set on 1 Ton for this lift.
c. 1 Ton setting provided the reach to install the engine in the ZR-1 while on KwikLift with Hood installed.

https://cimg3.ibsrv.net/gimg/www.cor...5cc9c973b3.jpg

2. TIPS and Notes Additional TIPS
a. ZR-1 on KwikLift with front lowered to assist in tilting engine to rear during installation.
b. Remove windshield wiper motor (drivers side). *
c. Engine was installed without the bell housing, plenum, fuel rails. **
d. Use custom design spreader bar under the load leveler and Harbor Freight 2 ton hydraulic lift. ***
e. With this setup, you can install LT5 in ZR1 on KwikLift with front of ZR1 facing forward (front of KwikLift on ground).
f. Leave hood on.
g. With this set up I have recently pulled an LT5 with SW Headers installed with no issues. You cannot use the standard lift eyes if you want to install the LT5 with headers however (use soft slings around Flywheel and Harmonic Balancer). See Installing Engine In ZR1

*Note: Reach through windshield wiper grille (the small removable access above windshield wiper motor arm connection). With socket wrench just loosen the two nuts on each windshield wiper arm (DO NOT REMOVE THOSE NUTS). Slide both windshield wiper arms off the motor sockets. Relube those windshield wiper sockets on the motor when reinstalling the windshield wiper arms. Remove the three bolts holding the windshield wiper motor in place and remove motor. Locate the wiper arm at 5:00 clock time looking toward front of engine. To reinstall the wiper arms reaching through the removable access with a long needle nose plyers you can slip the arms back on the socket and tighten the nuts after you reinstall the wiper motor. Relocate the wiper arm at its home postion before attaching the wiper arms (9:00 clock time looking toward front of engine). How to Replace the Wiper Motor

**Note: Install Cam Covers and plugs before installing the engine in the Z. This prevents anything from falling into the Camshaft area or Cylinders during engine installation. It is much easier to install Cam Covers with engine out of Z vice with engine installed (requires the loosening of "C" Beam Plates and Motor Mounts to tilt engine down in rear for access of two lower rear Drivers Side Cam Cover Bolts).

***Note: The custom design spread bar adapter was used to match the distance between the standard LT5 lift padeyes and Load Leveler lift points. The Load Leveler is attached to hydraulic lift on a swivel which allows the engine to be rotated around the vertical axis. You cannot use the standard lift eyes (shown in photo) if you want to install the LT5 with headers however (use soft slings around Flywheel and Harmonic Balancer).

https://cimg4.ibsrv.net/gimg/www.cor...16c3e1ca73.jpg

3. Summary Installing a LT5 in a 91' ZR-1
a. I removed the Wiper Motor as Ben suggested which was a 15 minute job. That removed the possible contact of the Wiper Motor with my powder coated Cam Covers while lowering the Harmonic Balancer past the front cross member :D

b. I installed the LT5 without Plenum, or Bell Housing. Those items were attached after the engine was installed in the Z.

c. I used KwikLift ramps sloped down in front for engine installation and then raised for completion of component installation.

d. It was easy sliding (KwikLift Creeper) under the Z for Bell Housing installation followed by Transmission and Drive Line installation with "C" Frame alignment.

e. That followed by SW Headers and SW exhaust system installation and adjustment.

f. The Ron Davis Radiator was then installed last adjusting ALL SAMCO coolant hose clamps for accessability using my flat screw driver. The last SAMCO hose installed was the short "L" on the drivers side IH Housing Coolant Manifold after filling with coolant making sure I had coolant at that level.

g. Installing the Plenum after engine installed was almost a necessity as the starter electric and Ignition Module (attached under the Plenum) electric was accessable only within the engine compartment. This also was a necessity for installation of the AC Compressor (before installation of the Plenum) under the Plenum (AC not disconnected). The Power Steering Pump was then connected to its position in front of the drivers side Head without disconnecting Power Steering Hydraulics.

h. I installed the Wiper Motor and Plenum after the engine was installed avoiding contact of the MAP sensor with the rear firewall. Installing the Wiper Motor and Plenum was a 15 minute job for each with engine installed. :cheers:

I wanted to get used to installing the Plenum with engine installed :D

The only thing I forgot to do before I installed the LT5 was check the Oil Pressure Regulating Valve (OPRV) Cover bolts for tightness which I later did but hard to accomplish with engine installed :hide:

Last UPDATE of post 15 Aug, 2017

Lifting and Towing the ZR-1
 

Lifting and Towing the ZR-1

See ZR-1 Transmission Install and Lift Tricks for a general discussion related to lifting the ZR-1 during transmission installation.

1. Lifting the ZR-1.
ZR1 Lifting techniques using a floor jack, jack stands and ramps are described herein. A Steel adapter has been designed and proven safe to lift the rear axle directly under the center of the rear spring mount using a floor jack. The ZR1 can be lifted to a height such that ramps can be inserted from the side under each rear wheel.

A Wooden Drive On Adapter has also been designed to get the front lift point (The front cross member just in front of the oil pan) high enough so a Floor Jack can be positioned under the Front Cross Frame (one Wooden Drive On Adapter is used under each front wheel). The Front Wooden Drive On Adapter consists of three 2x12s (you can see the approximate lengths of each of the three pieces) screwed together to form a single Wooden Drive On Lift. The Wooden Drive On Adapter allows you to drive on without interferring with the front skirt.

The ZR1 can then be driven off the ramps when work is completed without any further use of a floor jack. The adapter can be positioned on a floor jack lift pad and rolled under the spare tire area directly under the rear spring mount just behind the stock exhaust system.

The adapter is a 4 inch OD by 3/8 wall extra strong pipe section 5 inches long.

The pipe adapter is captured between the rear spring mount bolts, exhaust, spare tire on the ZR1 and by the floor jack lift pad which is usually cupped securing the pipe adapter from lateral movement.

The Steel Pipe Adapter
https://cimg6.ibsrv.net/gimg/www.cor...0c14fdb3e7.jpghttps://cimg7.ibsrv.net/gimg/www.cor...cac0c3d4d9.jpg

Lifting the Rear Axle
https://cimg8.ibsrv.net/gimg/www.cor...3389c11646.jpghttps://cimg9.ibsrv.net/gimg/www.cor...62561f62ce.jpg

The Drive Off Ramp under each rear wheel..................The Drive On Adapter under front wheels
https://cimg0.ibsrv.net/gimg/www.cor...f398c7d3da.jpghttps://cimg1.ibsrv.net/gimg/www.cor...1d2df56e15.jpg

Lifting The Front Cross Frame (note wood block between jack pad and cross frame)
When jacking the front center I use a 2x4x6 pad placed under the cross member so it is beneath the front part with the vertical stiffener. If you jack in the center of that cross member it will bend up a tad which you do not want to do.

https://cimg2.ibsrv.net/gimg/www.cor...e874e17b67.jpghttps://cimg3.ibsrv.net/gimg/www.cor...a0cbaf7271.jpg

Now it you jack up one side very high that does twist the body so I tend to limit the height I jack one side.
I just jack high enough at the side (just behind the front wheel) jacking points (not on the plastic but on the steel rim where it curves) to just getting the tire free of the ground for removal.

Front just behind front Wheel Well between two Hash Marks
https://cimg2.ibsrv.net/gimg/www.cor...7db2fac0af.jpg

Rear just in front of rear Wheel Well between two Hash Marks
https://cimg6.ibsrv.net/gimg/www.cor...7f09a56f12.jpg

The Best Jack is this 3 Ton Floor Jack from Harbor Frieght
https://cimg6.ibsrv.net/gimg/www.cor...98bfc2a095.jpg

2. Towing the ZR-1.

Emergency Kit.....15 ft tow rope (5,000 lb vehicle rating), Jumper Cables, Tow Adapter, Lug Wrench
https://cimg4.ibsrv.net/gimg/www.cor...2920b39d74.jpg

Daniel_Mc provided a concept/photo of a Tow Adapter for a ZR-1 that in its simplicity I just could not pass up :thumbs:
So......I designed one after the photo provided by Daniel_Mc and had a local steel shop fabricate the Tow Adapter.
I did some towing tests to see if there are any issues or limitations. One limitation will be towing at an angle in a turn which this adapter without being bolted on the back side of the cross member will not function (that did not seem to be an issue during the tow tests). The Tow Adapter is made from 1/8 inch steel plate which is substantial and flexible enough to tow the ZR-1 with Nylon Tow Ropes having a steel hook on one end.

https://cimg5.ibsrv.net/gimg/www.cor...b846f7353a.jpghttps://cimg6.ibsrv.net/gimg/www.cor...b8d4853830.jpg

The Tow Adapter is made to engage the 1-1/4 inch square tubing of the frame support under the front of the ZR-1.
https://cimg7.ibsrv.net/gimg/www.cor...b7a73484cb.jpghttps://cimg8.ibsrv.net/gimg/www.cor...5b99fea9b8.jpg

A. Tow Adapter Description.

When needed for towing, the Tow Adapter is slipped through a 4 inch x 1/8 inch slot in the front Air Spoiler. There are two 1/2 inch holes (not shown in photos) in the Tow Adapter plate (one for 90' and one for 91') depending on which model year you use the Tow Adapter. 1/4 inch Allen Head Bolts are inserted into one hole or other with large Pan Head Washers on each side (and adjusted snug against the Air Spoiler. The 1/4 inch Allen Head bolt keeps the Tow Adapter in place if you want to keep it installed as you drive.
https://cimg9.ibsrv.net/gimg/www.cor...ffdf8e2840.jpghttps://cimg0.ibsrv.net/gimg/www.cor...5559ec9e12.jpg

The best tool to make the 4 inch x 1/8 inch slot in the front Air Spoiler is an Angle Grinder (with Cut Off wheel).
The Tow Adapter sticks out beyond the skirt about 4 inches on a 91' and about 6 inches on a 90'.

https://cimg1.ibsrv.net/gimg/www.cor...fb2cb67502.jpghttps://cimg2.ibsrv.net/gimg/www.cor...8a7ecc9d8c.jpg

A nylon tow rope (a steel hook on the end is required) can be attached to the receiver in the Tow Adapter (2 inch x 2-1/2 inch hole).

B. Installing the Tow Adapter.

The Tow Adapter is simply installed by reaching under the Air Spoiler and inserting the front tip of the Tow Adapter into the slot in the Air Spoiler. Push forward and then lightly tap the rear of the Tow Adapter onto the cross member with a small hammer. The Tow Adapter is removed by lightly tapping on the front tip of the Tow Adapter with a small hammer.

C. Testing Tow Adapter.

The Tow Adapter was tested towing the 91' ZR-1 with a lawn tractor on gravel. A small nylon sling was used for towing. The Tow Adapter was NOT bolted to the frame in any way.

https://cimg4.ibsrv.net/gimg/www.cor...a87d313265.jpghttps://cimg6.ibsrv.net/gimg/www.cor...6d13d3eca8.jpg

When towing at an angle of 45 degrees the front wheels were turned in the direction of towing. With a lawn tractor and the use of this Tow Adapter, the ZR-1 could be backed into the street and with a lawn tractor pulled and then releasing the clutch in second gear starting the engine if your battery is dead. There was no deformation of the Tow Adapter during these tests :thumbs:

Towing in a straight line......................................... ...Towing at an angle of 45 degrees.
https://cimg9.ibsrv.net/gimg/www.cor...08c5e90ae1.jpghttps://cimg0.ibsrv.net/gimg/www.cor...5119712cba.jpg

D. Storing Tow Adapter.

I have elected to carry the tow adapter on the right side of the passenger seat where it fits perfectly with my Gorilla Lug Wrench. I have found with the tow adapter installed it is easy to hit it with a curb when parking. It is very easy to slip in place if needed without jacking the vehicle.

Tow Adapter Stored next to Passenger Seat......................Gorilla Lug Wrench
https://cimg1.ibsrv.net/gimg/www.cor...0c84862568.jpghttps://cimg2.ibsrv.net/gimg/www.cor...625a82bb07.jpg


Last UPDATE of post 16 Mar, 2018

Tremendous post! Great Job & Thank You for your time & effort in putting it together. :rock:

Engine Lubrication System Functional Discussion
 

The Oil Filter Adapter has many important functions. The Oil Filter Adapter is NOT for the sole purpose of holding/adapting the Oil Filter.

The oil paths through the Oil Filter Adapter Housing are describe in Item #5 below.

1. A Discussion of the Functions of the Oil Filter Adapter.
a. Control Oil Temperature. See Related ECM Code #52 Item #3 ZR1 ECM CODES 1990 TO 1992
b. Provide Sensor Feedback to the Instrument Panel.
c. Provide Oil Filtration.
d. Assure proper Oil Flow at any Oil Temperature.
e. Assure proper Oil Flow with contaminated Oil Filters.

The Oil Pressure Regulating Valve situated between the Oil Pump and Oil Filter Adapter controls and maintains Consistent Oil Pressure.

As an aside
2. Oil Pressure Sensor (Dash Gauge) Malfunction I changed out the oil pressure sensor for the dash gauge (top of oil filter) after engine installation. Oil pressure cold was registering 75 lbs. After changing out the oil pressure sensor, oil pressure is registering 55 lbs steady hot or cold and does not increase much with revs.

Oil Filter Adapter Sensors ........................................ ......Oil Filter Adapter Ports and Sensors
https://cimg8.ibsrv.net/gimg/www.cor...9b8c61ffd4.jpghttps://cimg9.ibsrv.net/gimg/www.cor...ed65e13e8c.jpg

3. LT5 Oil Pressure and Oil Temperature Regulation

a. The Oil Pressure Regulation Valve (OPRV) (just after oil pump) opening pressure is 50-60 psi.

https://cimg0.ibsrv.net/gimg/www.cor...27c95368f6.jpghttps://cimg2.ibsrv.net/gimg/www.cor...5879d8e082.jpg

b. The Oil Cooler Bypass Valve on the Oil Filter Adapter allows oil to bypass the open oil cooler at hot temperatures since oil cooler is a bit restrictive. This valve raises the pressure a bit on the flow trying to bypass the oil cooler making sure some oil does go through the oil cooler.
c. The Oil Temperature Control Valve on oil filter housing opens oil flow from the oil cooler. The temperature opening characteristics of this valve are Thermostat-Open-203 degree F, Fully open-266 degree F.
d. The Oil Filter Bypass Valve on oil filter housing allows oil to bypass oil filter if the oil filter becomes to restrictive.
e. Oil pressure is always available to the Oil Cooler Bypass Valve. Oil flows from the oil pump (past the OPRV) to the oil filter through the Oil cooler and through the Oil Cooler Bypass Valve or directly through the Oil Temperature Control valve when the oil temperature is below 203 deg F. The oil cooler flow return and Oil Cooler Bypass Valve are open at the same time. The oil flow from the oil cooler is never totally blocked (half moon cutout of shuttle valve). The Oil pump flow at Idle is 1.6 gpm and the Oil pump flow at 7,000 rpm is 9.1 gpm.

4. Oil Filter Adapter Functional Details

Oil Temperature Control Valve Assembly.....................Oil Temperature Valve Thermostat opens at 203 deg F
https://cimg3.ibsrv.net/gimg/www.cor...d4eafe8fc0.jpghttps://cimg4.ibsrv.net/gimg/www.cor...4195402d1f.jpg

Oil Temperature Shuttle Valve Open (HOT)............................Oil Termperature Shuttle Valve Closed (COLD)
https://cimg5.ibsrv.net/gimg/www.cor...ae23615b85.jpghttps://cimg6.ibsrv.net/gimg/www.cor...8df8b1de68.jpg

Oil Cooler Bypass Valve Inside........................................ ..........Oil Cooler Bypass Valve Outside
This valve raises the pressure a bit on the flow
trying to bypass the oil cooler making sure some
oil does go through the oil cooler.
https://cimg7.ibsrv.net/gimg/www.cor...11412fa1a5.jpghttps://cimg8.ibsrv.net/gimg/www.cor...15c409f497.jpg

Oil Temperature Control Valve Compensation..............Oil Filter Adapter (Oil Temperature Valve Housing)
The orifice allows the valve to move
without being hydraulically locked in place.
https://cimg9.ibsrv.net/gimg/www.cor...db6e15873e.jpghttps://cimg1.ibsrv.net/gimg/www.cor...5389a91e2a.jpg

5. Oil Flow Paths.

COLD - Oil Temperature Less than 203 deg F.
a. The Oil is pushed up from the bottom Port on the Oil Filter Adapter Housing past the TOP Oil Cooler Port which is ALWAYS OPEN.
b. The Oil then is pushed through the Top Opening of the Oil Temperature Control Valve to the bottom of the Temperature Control Valve Port.
c. The Oil is also pushed against the Oil Cooler Bypass Valve which it will not open since the path through the Temperature Control Valve Port is Open.
d. Some Oil flows through the Oil Cooler back into the Bottom Oil Cooler Port since the Bottom of the Temperature Control Valve has a Half Moon Port that is Always Open.
e. The Oil then pushed up through the Oil Filter Outside Diameter and also against the Oil FIlter Bypass Valve just in case the Oil Filter is too Restrictive.
d. The Oil is then pushed out the center Oil Filter Adapter Fitting (M20x1.5) past the Oil Pressure Sensor for Dash Gauge, past the Oil Temperature Sensor, and past the Oil Pressure Switch Light on Dash Sensor out the Top of the Bottom Ports of the Oil Filter Housing Adapter to the Crankshaft and Top End Camshafts. The Oil pressurizes and lubricates the Timing Chain Tensioners and Timing Chains as the oil flows.
See Timing Chain Idler Sprocket Lubrication and Installation

WARM - Oil Temperature greater than 203 deg F but less than 266 deg F.
a. The direct Oil Path to the Oil Filter through the Oil Temperature Control Valve is not yet closed but is becoming Restrictive.
b. The Bottom Port of the Oil Temperature Control Valve is Opening beyond the Half Moon Port.
c. The Oil Path around the Oil Temperature Control Valve through the Oil Cooler Bypass Valve may come into play.
d. The Oil is then pushed out the center Oil Filter Adapter Fitting (M20x1.5) past the Oil Pressure Sensor for Dash Gauge, past the Oil Temperature Sensor, and past the Oil Pressure Switch Light on Dash Sensor out the Top of the Bottom Ports of the Oil Filter Housing Adapter to the Crankshaft and Top End Camshafts. The Oil pressurizes and lubricates the Timing Chain Tensioners and Timing Chains as the oil flows.
See Timing Chain Idler Sprocket Lubrication and Installation

HOT - Oil Temperature greater than 266 deg F.
a. The Top of the Oil Temperature Control Valve Port Through the Oil Temperature Control Valve is now completely Closed.
b. All Oil is directed through the Oil Cooler (Top Oil Cooler Port) or through the Oil Cooler Bypass Valve around (outside) the top of the Oil Temperature Control Valve.
c. The Bottom of the Oil Temperature Control Valve Port is now completely open allowing Oil to go from the Oil Cooler through the bottom of the Oil Temperature Control Valve directly to the Oil Filter and Oil Filter Bypass Valve.
d. Some Oil passing through the Oil Cooler Bypass Valve will flow directly to the Oil Filter and Oil Filter Bypass Valve depending on the Restrictions to Oil Flow through the Oil Cooler.
e. The Oil is then pushed out the center Oil Filter Adapter Fitting (M20x1.5) past the Oil Pressure Sensor for Dash Gauge, past the Oil Temperature Sensor, and past the Oil Pressure Switch Light on Dash Sensor out the Top of the Bottom Ports of the Oil Filter Housing Adapter to the Crankshaft and Top End Camshafts. The Oil pressurizes and lubricates the Timing Chain Tensioners and Timing Chains as the oil flows.
See Timing Chain Idler Sprocket Lubrication and Installation

6. There IS an Oil Level Sensor on the 91'-95' ZR-1 Oil Pan.

The Oil Pan for 1990, 91 & 92 are interchangable with the only difference being, the 1990 LT5 engine was not equipped with a Low Oil Level Sensor. The extra material was cast into the pan but not machined for the screw-in sensor. As such, the oil level indicator would not be functional if the 1990 oil pan is used for 1991 & 1992 applications Oil Level Sensor TIPS

Brass Oil Level Sensor 93'-95' Jerrys Brass Oil Level Sensor 93' to 95'
https://cimg2.ibsrv.net/gimg/www.cor...ff0763a056.jpghttps://cimg5.ibsrv.net/gimg/www.cor...8ea3d161dd.jpg

Plastic oil Level Sensor 91'-92' Summit Racing Oil Level Sensor
Jerrys Plastic Oil Level Sensor
https://cimg4.ibsrv.net/gimg/www.cor...d870e20918.jpghttps://cimg6.ibsrv.net/gimg/www.cor...0233004e4a.png
https://cimg3.ibsrv.net/gimg/www.cor...80865bc748.jpg

Last UPDATE of post 18 Dec, 2017

LT5 Lubrication Tricks and Replace Dipstick Handle
 

LT5 Lubrication Tricks

1. Oil Pressure Switch Rotated.
The Oil Pressure Switch was rotated 90 deg which allows for easy access.
The additional JIC connection (capped in photo) allows for a Pre Oiler or mechanical oil pressure gauge connection.

Oil Pressure Switch rotated 90 Deg
https://cimg3.ibsrv.net/gimg/www.cor...71ead82ca6.jpg

Background - LT5 Oil Pressure Regulation

The Oil Pressure Regulation Valve (just after oil pump) opening pressure is 50-60 psi Oil Pressure Regulation Valve

The Oil Cooler Bypass Valve on oil filter housing allows oil to bypass the open oil cooler at hot temperatures since oil cooler is a bit restrictive. This valve raises the pressure a bit on the flow trying to bypass the oil cooler making sure some oil does go through the oil cooler.

The Oil Temperature Control Valve on oil filter housing opens oil flow from the oil cooler. The temperature opening characteristics of this valve are Thermostat-Open-203 degree F, Fully open-266 degree F.

The Oil Filter Bypass Valve on oil filter housing allows oil to bypass oil filter if the oil filter becomes to restrictive.

It appears that oil flow is always open to the Oil Cooler Bypass Valve. Oil is not always open directly from the oil pump to the oil filter except through the Oil cooler and Oil Cooler Bypass Valve when the flow from the oil cooler is open. The oil cooler flow return and Oil Cooler Bypass Valve are open at the same time. When the oil flow from the oil cooler is blocked, the oil from oil pump to oil filter is open flow. Oil pump flow at Idle-1.6 gpm, Oil pump flow at 7,000 rpm-9.1 gpm.

As an aside, the after market SS oil cooler lines and aluminum manifold are a bit larger ID than stock with 10AN aeroquip reusable hose end fittings (1/2 inch ID). The 10AN adapter at the aluminum manifold (appears to be M18 x 1.5 or 10AN O ring straight thread) adapts the 10AN ID to the stock manifold hose ID (appears to be 3/8 inch). On the other end at the oil filter housing, the 10AN SS oil cooler line fittings adapt to the 12AN oil filter housing fittings. The stock oil cooler lines have 12AN fittings but smaller than 10AN hose ID.

2. Oil Catch Can.
The Elite Oil Catch Can is attached directly to the front of plenum vacuum source and directly to the PVC connection (use 1/4 inch brass m/m hose nipple) at rear of plenum using SS Braided hose and reusable swivel hose fittings.

Elite Oil Catch Can
https://cimg4.ibsrv.net/gimg/www.cor...90de338c0d.jpg
https://cimg6.ibsrv.net/gimg/www.cor...8e1113ced7.jpg

a. Used a small steel channel (about 3/8 x 1 x 6 inches) which the flanges are ground to fit the curve of the inside wheel well (at a 45 deg angle).
b. Drilled two 3/8 inch holes in the steel channel to fit the hanger that came with the Oil Catch Can.
c. Drilled two holes to match in wheel well to match.
d. The fit of the oil catch can is very tight against inside of wheel well.
e. Oil Catch Can sits directly above the upper A-Arm rear pivot within 1/2 inch of the pivot.
f. Painted the steel channel black.
g. Used small steel hose clamps on each end of SS Braided hose which keeps hose SS braid from fraying.

https://cimg7.ibsrv.net/gimg/www.cor...321ebeaeaa.jpg

The Oil Catch Can Mount was attached using 1/4 inch Wing Nuts for easy removal. The PCV Nipple is 1/4 inch brass male/male installed in PVC rubber connector.
Oil Catch can Elite Engineering USA
SS Braided hose Summit Racing Braided Hose
Hose ends Summit Racing Hose Ends

https://cimg8.ibsrv.net/gimg/www.cor...333640a476.jpghttps://cimg9.ibsrv.net/gimg/www.cor...8ba0f7eeee.jpg

3. Dipstick Handle Replace.
The Dipstick Handle which is Plastic is usually cracked. I replaced the handle with a Chrome Oil Dipstick Handle

https://cimg6.ibsrv.net/gimg/www.cor...7eaa9db4a9.jpg

I removed the cracked Plastic Stock Dipstick Handle. Once removed, there is a FLAT with a dimple. I drilled the dimple through with a 5/32 drill bit. I then put that end of the dipstick to a grinder and shortened that end so the hole I drilled lined up with the New Chrome Dipstick Allen Head Bolt hole.
https://cimg1.ibsrv.net/gimg/www.cor...36079dfb97.jpg

The Chrome Dipstick Handle (5/32" Diameter Allen Head screw with 2.5mm hex Allen head) was then installed using several small brass washers (approximately 5/32" ID) to secure/compress the existing shaft between the two halves of the New Chrome Dipstick Handle.

Dipstick Handle showing 2.5mm Allen Head Screw ...........Chrome Dipstick Handle Installed showing Brass Washers
https://cimg2.ibsrv.net/gimg/www.cor...81eec4fa99.jpghttps://cimg3.ibsrv.net/gimg/www.cor...28df10d7ee.jpg

The existing straight portion of the Dipstick was then placed in a vice and the handle bent and twisted to align the Chrome Handle with the Cam Covers similar to the original alignment.

The New Billet Aluminum Dipstick with BIG RED OIL Letters fits perfectly with the Billet Aluminum Oil Fill Cap I found on Ebay
Search Ebay CORVETTE LT1 BILLET CHROME SCREW IN STYLE OIL CAP Ebay Billet Aluminum Oil Cap (fits 90' & 91' LT5 & L98).


https://cimg4.ibsrv.net/gimg/www.cor...32189a8dac.jpghttps://cimg5.ibsrv.net/gimg/www.cor...38d4c5d975.jpg

If you place the stock Dipstick in a vice at the flat just below the first squiggles and then with Dipstick Handled INSTALLED...you can twist the Stock Dipstick any direction you want but you have to go over center to make the twist stay. You can also bend the part between the collar and handle but you then have to keep the Dipstick from turning. So it is not too easy for some.......I was about to take a torch and heat the Stock Dipstick End before I figured out that hardened metal Dipstick could be twisted and bent without breaking.

The beauty of the Stock Dipstick is if you break off the cheap Plastic Handle there is a very nice FLAT with that dimple where the outer part of the top part is swedged onto the smaller Flat making a slighty LARGER Flat to work with.

I was going to enclose the bottom of the New Chrome Dipstick Handle with JB Weld but found that not necessary because it absolutely does not show at all until you remove the Dipstick. I may enclose that area with some JB Weld and Rustoleum Black Heat Resistant Paint.

Last UPDATE of post 19 Nov, 2020

Potential Oil Leaks and the OPRV Cover Plate
 

Potential Oil Leaks and the OPRV Cover Plate

1. Potential Oil Leaks.

A. OPRV (Oil Pressure Regulating Valve cover plate )......It will appear that the oil pan front bolts are loose and leaking at gasket.
B. Oil Pressure Switch and Oil Pressure Sensor.....
C. Cam Covers.....
D. Camshaft circular rubber plugs (two each end of each Head).....
E. Oil Cooler Hoses/Connections.....
F. There is an Oil Level Sensor on Oil Pan....(not on 1990).
G. Oil Pan Bolts (especially front three 8mm bolts).
H. Center Bolt/Stud on Exhaust Manifold (one each side).
But I would say the one that stumped me the most was that OPRV cover. And prolly the hardest to get at (two 6 mm bolts using an 8 mm Socket wrench).

Marc Haibeck Oil Leak Summary

The most common oil leak is an oil pan gasket leak which is often misdiagnosed. What is really leaking is the Oil Pressure Regulating Valve Cover Plate. It will appear as a drip of oil and oily surface on the right front of the oil pan. Often the tendency is to tighten the front oil pan bolts with no success on stopping the oil leak. The Oil Pressure Regulating Valve Cover leak can also be misdiagnosed as a Front Crankshaft Seal leak. The symptoms are a film of oil progressing rearward on bottom of oil pan or an actual drip of oil on the right front oil pan bolts.

2. Oil Pressure Regulating Valve Cover Plate (1990-1991 ZR-1).

The Oil Presure Regulating Valve is located on passenger side front of engine just above the oil pan. The two 6 mm bolts that hold the OPRV cover plate (and gasket) to the Engine sometimes come loose.

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There is an OPRV Cover plate gasket but I just removed and cleaned the two 6 mm bolts (8 mm heads) one at a time and applied Blue Loctite (You could use Red Loctite as you like). I used Blue Loctite because I figured it was a temporary fix but appears to be a permanent fix. I reached in from the top front of the engine to get access to the two 6 mm bolts with an 8 mm hex flex head ratchet wrench. An easier method of access to the Oil Pressure Regulating Valve Cover Plate is from the bottom as described in item #3 below.

Somtimes interlock an open end box wrench (box end interlocked with open end of flex head rachet wrench)
to gain length for that bolt out of normal reach.

Since such a tight area to work in with engine in car I removed each 6 mm bolt one at a time so I did not drop the cover plate or gasket. So...no permatex on that gasket but both 6 mm bolts cleaned and Blue Loctite applied.

Since the bolts and plate were so loose I figured correctly just tightening the 6 mm bolts with Blue Loctite would solve the oil leak and loose bolt problem (The gasket was stuck to the engine block and not the cover plate). I tightened the bolts by feel as I could not get torque wrench even close to that area unless engine is out of car. No more oil leaks in that area at all.

The BEST fix, however, is to replace those two 6mm x 15mm bolts having 8mm heads with two 6mm x 15mm bolts with 10mm heads as described in item #3 below.

Torque for 6 mm bolts is about 89 in-lbs but in that area with no oil pressure to contend with less bolt torque with Blue Loctite or maybe Red Loctite is just fine :thumbsup:

3. Oil Pressure Regulating Valve Cover Plate (1995 ZR-1).

On the 1995 ZR-1 the Oil Pressure Valve Cover Plate is impossible to get to from above because of the EGR. But....one can get to that Cover Plate from below by removing the Passenger side strut that the Passenger Side Motor Mount is bolted to (no pressure on that strut from motor mount). Remove two 15mm bolts toward front and two 13mm bolts on frame rail passenger side. Remove 18mm Nut from Motor Mount Stud and drop the strut. The Oil Pressure Valve Cover Plate can be easily seen toward front where Strut was positioned. The bottom 6mm bolt is easy to unscrew and the top 6mm bolt required a vice grips gripping an 8mm open end to loosen. Both 6mm x 15mm Bolts with 8mm Heads were replaced with 6mm x 15mm Bolts with 10mm Heads.

https://cimg7.ibsrv.net/gimg/www.cor...95e480a52e.jpghttps://cimg8.ibsrv.net/gimg/www.cor...9e0db87d7f.jpg

4. The Trick to STOP oil leaks from the Oil Pressure Control Valve Cover plate.

I replace both top and bottom 6mm x 15mm bolts with 6mm x 15mm Flange Bolts (Ebay and as pictured above) that have a 10mm head for a 10mm Box or ratchet Box wrench. It is a lot easier to tighten a 10mm bolt than an 8mm bolt which sometimes strips in the small 8mm box wrench. I used Red Loctite on the 6mm x 16mm Flange Bolts. No need to remove the Oil Pressure Valve Cover Plate or associated gasket.

https://cimg0.ibsrv.net/gimg/www.cor...87fb06aa31.jpg

Two 6mm x 15mm Flange Bolts installed in Oil Pressure Regulator Valve Cover (10mm Heads)
replacing original 6mm x 15mm (8mm Heads) Bolts.
Top 6mm Bolt shown before tightening with 10mm Box Wrench

https://cimg1.ibsrv.net/gimg/www.cor...a1dcf53faa.jpg

Last UPDATE of post 20 Mar, 2018

LT5 Camshaft Specifications and Camshaft General Timing (pinning)
 

LT5 Camshaft Specifications and Camshaft General Timing (pinning)

1. Reground Camshafts Specifications.

425 intake .420 exhaust
Regrind Intake Camshaft .236 .425 (Pete)
Regrind Exhaust Camshaft .220 .425 (Pete)
Camshaft Timing........114 deg ATDC Intake 110 BTDC Exhaust

Camshaft Identifications

1 flat RH Intake
1 raised RH Exhaust
1 flat,1 raised LH Intake
2 raised LH Exhaust

https://cimg3.ibsrv.net/gimg/www.cor...d9948b950d.jpghttps://cimg0.ibsrv.net/gimg/www.cor...e5273a2451.jpg

2. Camshaft General Timing by Pinning.

a. Set the camshaft timing relatively close using the pinning method (using a 15/64 drill bit as a pin).
b. Use Cylinder #1 for drivers side bank and Cylinder #6 for passenger side bank.
c. Install Timing Chain temporary manual tensioners.

Use Jeffvette Billet Aluminum Camshaft Retainers which will remain in place after camshaft timing is complete.

To start the cam timing process rotate the crankshaft to the 51 deg mark BTDC on the front pulley aligned with "0" on timing plate (degree wheel installed on front crankshaft pulley).
Keep in mind that this discussion is for the Drivers side Heads. For the Passenger side Heads use cylinder number 6 instead of cylinder number 1 when setting the camshaft timing using the degree wheel with the method of finding maximum cam lift. TDC for cylinder number 6 will be 360 deg from cylinder number 1. 114 deg ATDC IN and 110 deg BTDC EX will be related to the TDC of cylinder number 6..

Install all cams in the neutral position (no lifters being compressed) using the Billet Aluminum (oiled) Camshaft Retainers with Torx bolts tightened (89 in-lbs) with loctite 262.

Looking at the front of the engine toward the rear so clockwise is normal engine rotation from that perspective.

Rotate exhaust camshafts to insert a 15/64 drill bit as a pin into the pinning hole in exhaust camshafts (hole in front camshaft Retainer). Pin counterclockwise one pin hole to allow for 110 deg BTDC EX. Rotate intake camshafts to insert 15/64 drill bit as a pin into the pinning hole in intake camshafts (hole in front camshaft Retainer) as that should be close to 114 deg ATDC IN.

The Pinning Method will get you close to these timing numbers (110 deg BTDC EX and 114 deg ATDC IN). Fine tuning the camshaft timing for a ported engine (for example), use the degree wheel and a dial gauge on the lifters for the additional fine camshaft timing adjustments. See step 5c of LT5 Camshaft Timing Additional Tricks

Rotate the camshaft sprockets counterclockwise against the chain, and then set vernier plate pin in "next" hole clockwise where the pin might fit. Then tighten a bit the camshaft bolts such that the "flat" of the camshaft is counterclockwise tight against the flat of the vernier plate which was rotated clockwise (holding a 19 mm box wrench on the rear end of the camshaft).


Last UPDATE of post 21 Aug, 2017

LT5 Camshaft Specific Timing (degree wheel)
 

LT5 Camshaft Specific Timing (degree wheel)

1. Degree Wheel.

That degree wheel provided by bdw18_123 was used.
I reduced the image size (actual printed diameter) to 7.08 inches when printing and glued it on the front pully with my 51 deg BTDC, 114 deg ATDC, 110 deg BTDC, and TDC marked on the wheel. I cut a 4 inch hole in the center of the degree wheel print out before I glued it so I could get my 13/16 inch wrench on the front pully bolt.

I used that degree wheel to place marks on the inside of the front pully.

https://cimg1.ibsrv.net/gimg/www.cor...6dafbbfb99.jpg

I could then align degree wheel marks with the factory timing plate Advance Marks and TDC "O" Mark attached to the front of the engine (drivers side) almost touching the inside of the front pully. Making sure I was always on #1 cylinder compression stroke.

2. Determine TDC on the Harmonic Balancer.

The first thing to do is verify TDC. Always rotate the crankshaft clockwise looking at front of engine.


I checked my mark on the Harmonic Balancer for TDC. I set up a dial indicator on cylinder number one. The piston moved .029 inch before and .029 inch after TDC which was exactly 10 deg before and 10 deg after my mark on the front pully. My TDC mark on front pully is right on the money.

https://cimg4.ibsrv.net/gimg/www.cor...90b9a4615a.jpg

3. Camshaft Sprocket and Venier Plate.

There are 20 teeth on the cam sprocket or 18 degrees per tooth. There are 14 holes in sprocket or 25.7 degrees if you rotate vernier plate without removing pin from hole in vernier plate and pin next hole in sprocket (15 holes in vernier plate and 14 holes in sprocket). There is 1.6 deg on the camshaft sprocket if you rotate vernier washer to align with next pin hole in sprocket (360/15/15). So if you went 11 holes that would be like one tooth on camshaft sprocket or 17.6 degrees on the camshaft sprocket retard or advance. The smallest amount of retard or advance you could set would be 1.6 deg on the camshaft sprocket by pinning next aligned holes (3.2 deg on the Harmonic Balancer).

Marc Haibeck suggests there is about 3 deg of play (6 deg measured at the crankshaft) between the sprocket timing plate flat (vernier plate) and camshaft flat (90'-92'). This is reduced to 1.5 deg (3 deg measured at the crankshaft) on 93s' (having double flats). As one tightens the camshaft bolt you have to watch not to turn the camshaft in the timing plate (vernier plate). It helps to hold a 19 mm open end wrench on the rear of each cam during tightening of the camshaft bolt.

This 3 deg of play (at the camshaft) actually allows you to set the camshaft timing at any angle within the 1.6 deg (at the camshaft) allowed by the pin holes in the vernier plate and sprocket.

Marc Haibeck has upgraded his article "Timing the LT5 Camshafts" to .pdf on his website Timing LT5 Camshafts

4. Timing Camshafts 114 deg ATDC Intake and 110 deg BTDC Exhaust.

I will use a similar setup with the dial indicator on the intake and exhaust primary lifters for cylinder number one (left Head) and cylinder number six (right Head) to determine crankshaft angle at camshaft maximum lift. I will first mark 114 ATDC and 110 BTDC on the Harmonic Balancer and set dial gauge up on lifters to verify intakes at 114 deg ATDC and exhaust at 110 deg BTDC on number one cylinder.

Marc suggests to have a broad torque and power range (3000 to 7000 rpm) use Intake 114 ATDC and Exhaust 110 BTDC. 114/114 is nice when trying to tame idle roughness out of a engine having modified Camshafts.

What you want is equal lifter depression before and after max lifter depression noting the crankshaft rotation degrees (degree wheel set up on front of crankshaft pully) before and after max lift set up on (No. 6 cylinder passsenger side and No. 1 cylinder drivers side). For Intake example you might see equal lifter depression at 104 deg ATDC and 124 deg ATDC and splitting the difference would be 114 deg ATDC. You do the equal lifter depression "trick" because it is almost impossible to see max lifter depression using a dial gauge within say 5 deg either way as the cam lobe rotates over the flat.

Marc Haibeck suggests positioning the cam at .010" before top of lift and .010" after top of lift point where .001" change in lift is about 1 degree of cam rotation.

If I am off on the camshaft timing, I will adjust vernier plate and/or re-pin sprocket and re-snug the camshaft bolt and verify again. Once I have the correct camshaft timing I will final tighten the camshaft bolts without moving the camshaft. See step 5c of LT5 Camshaft Timing Additional Tricks

If I am OK (110 deg BTDC EX and 114 deg ATDC IN), I will tighten the camshaft bolts without moving camshaft (an extremely important step since Marc has seen significant evidence of camshaft shifting after the camshaft bolt is torqued on many engines). I will re-intall the aluminum CNC camshaft retainers installed with cardboard spacer to take out slop and to hold camshaft when I tighten front camshaft bolt (using 19 mm box wrench on the other end of camshaft).

I will Use Loctite 262 on the camshaft bolt, and lubricate both sides of the washer. Tighten to 19 ft lbs and then mark a straight line and then proceed to tighten (Stretch) the bolt (Marc's Camshaft Bolts) another 80-85 degrees (while holding a 19 mm box wrench on the other end of the camshaft).

After the camshaft timing is set, I will remove the manual chain tensioners and install the factory hydraulic chain tensioners set in travel position. I will give the chain tensioners a tap to activate each tensioner.

Last UPDATE of post 22 Aug, 2017

LT5 Camshaft Timing Additional Tricks
 

LT5 Camshaft Timing Additional Tricks

1. First make sure of TDC
If you want to make sure of the TDC marks on the Harmonic Balancer, you can install a dial gauge to determine when piston #1 is TDC to determine TDC easy enough engine in car and can then mark harmonic balancer and use degree tab bracket easy enough engine in car. The Tab has marks 25 deg Before and 5 deg After TDC. Always rotate the crankshaft clockwise looking at front of engine. The Tab has marks 25 deg Before and 5 deg After TDC (A total of 30 deg). You can use the marks on the Timing Tab to mark your Harmonic Balancer. Mark 110 deg BTDC by rotating the Harmonic Balancer 3 complete Tabs (90 deg) + 20 deg Counter Clockwise and mark. Mark 114 deg ATDC by rotating the Harmonic Balancer Clockwise 3 complete Tabs (90 deg) + 24 deg and mark.

See Item #2 Camshaft Timing

https://cimg4.ibsrv.net/gimg/www.cor...90b9a4615a.jpg

2. Marking Camshaft Journal and Sprocket.

Ben's Trick Marking the cam journal and sprocket (just behind the sprocket) helps considerably keeping track of where you are in the camshaft timing process as Ben suggested (Ben's photo below). You know right away if things have moved on you.

Ben's (bdw18_123) photo Bens great restoration of a 90' ZR1

https://cimg6.ibsrv.net/gimg/www.cor...e7b3a6ad96.jpg

3. Use Old Camshaft bolts to set the Camshafts.

Another Ben trick is to use the old camshaft bolts (snugged up to prevent the camshafts from popping forward or backward) during the timing process and then with the camshaft in a position where it will not pop or rotate backward or forward (best achieved with one set of valves at maximum opening), switch to the new camshaft bolts (with red loctite) for final camshaft bolt tightening.

4. Using a Dial Gauge.

A third trick is to use Lee's Harbor Freight Flexible Arm to hold the dial gage when measuring lifter movement. Harbor Freight Flesible Arm

5. Installation of New Camshaft Bolts.

After you degrease the new camshaft bolts, use plenty of red (262) Loctite on the camshaft bolts.

a. Jerry's Camshaft Bolts ---- 80 ft-lbs torque
b. Marc's Camshaft Bolts -----18 ft-lbs + 80 deg rotation of camshaft bolt.

6. Venier plate movement.

a. For a (90-92 LT5) there is 6 deg of crankshaft play when the camshaft flat rotates 3 deg against the flat of the venier plate (flat to flat).
b. It has also been calculated that each pin hole advance or retard moves the camshaft 1.6 deg (3.2 deg at crankshaft).
c. Set up with the camshaft venier plate rotated against the camshaft flat (clockwise looking at front of engine). Forget about the 6 deg of crankshaft play (3 deg in the venier plate flat to flat) relative to camshaft movement for the moment.

7. Checking Actual Valve Maximum Opening Degrees.

Check actual valve max opening (shooting for 114 deg ATDC INTAKE for example) using equal Lifter movement before and after max valve opening.
a. Look for .015 less than maximum lifter movement either side of maximum valve opening as you rotate the crankshaft (clockwise looking at front of engine) through max valve lift.
b. If you have maximum valve opening at 112 deg ATDC (2 deg off) you have to rotate the camshaft and venier plate clockwise with respect to the camshaft sprocket one peg hole or 3.2 deg crankshaft rotation which would put you at 115.2 deg ATDC next check.
[B]c. The venier plate could now be rotated counterclockwise looking at front of engine 3 deg within the total play in the venier plate by locking the venier plate tight in the counterclockwise direction against the camshaft. In this case keep the venier plate locked in the clockwise direction (looking at front of engine) against the camshaft to eliminate this larger potential adjustment/play consideration which would amount to 6 deg of crankshaft rotation.

8. Tightening the Camshaft Bolt.

It is difficult to tighten the camshaft venier plate down on the camshaft with the flat of the venier plate somewhere within the 3 deg of play (6 deg of crankshaft rotation) where the venier plate can rotate back and forth on the camshaft.
a. The Trick is to lock the venier plate flat in the most clockwise direction (clockwise looking at front of engine) tight against the flat of the camshaft.

https://cimg7.ibsrv.net/gimg/www.cor...bd3c7aee31.jpghttps://cimg0.ibsrv.net/gimg/www.cor...e5273a2451.jpg


Notes:

1. The worst you could be off (INTAKE Camshaft 114 deg ATDC example) would be 1.6 deg crankshaft rotation if you were at or greater than 115.6 deg ATDC or at or less than 112.4 deg ATDC first check. Just leave well enough alone (any degrees between 115.6 and 112.4 deg ATDC). [B]Either is very close and within measurement error (determining maximum lifter lift by any method within 1 deg is very difficult) of 114 deg ATDC desired INTAKE camshaft timing or 110 deg BTDC EXHAUST camshaft timing.

2. Keeping the venier plate locked in the clockwise direction against the camshaft flat eliminates the venier plate rotation when tightening the camshaft bolt while holding the camshaft from rotating on the other end with a box wrench.

3. This technique simplifies the adjustment and assures the camshaft sprocket venier plate flat is always against the flat of the camshaft rotating clockwise looking at front of engine (less chance for the venier plate to rotate and venier plate/camshaft flats to move relative to one another during or after camshaft bolt tightening).

Last UPDATE of post 23 Aug, 2017

LT5 Timing Diagrams and Timing Chain Effective Lengths
 

LT5 Timing Diagrams and Timing Chain Effective Lengths

1. Timing Diagrams.

https://cimg2.ibsrv.net/gimg/www.cor...5d7136c5a8.png

The Timing Chain Effective Lengths depends on Timing Chain Tightness and Chain Guide Wear...theory under development testing as we speak.

2. Timing Chain Effective Lengths.

The crankshaft rotates clockwise looking at front of engine. The Timing Chain Tensioners are located on the bottom (passenger side) chain before Camshaft Sprockets and on the top (drivers side) chain before Camshaft Sprockets. The chain between and after the Camshaft Sprockets returning to the timing chain Idler Sprocket is normally relatively tight. That section of the Timing Chain remains relatively tight as long as the crankshaft is rotated in a normal direction and as long as cams do not push back (lifters pushing the camshafts clockwise). Timing chain Effective Lengths are related directly to timing chain tightness and Timing Chain paths as directed by the Timing Chain Guides (That path changes with Timing Chain Guide wear).

a. Chain Tension different with engine runing as compared to the Camshaft Timing Process.
If the Timing Chains are tighter during engine running with hydraulic lifters pressurized the Exhaust camshafts may be advanced a degree and the Intake camshafts may be retarded by a degree. For Exhaust camshafts at 110 deg BTDC may actually advance to 111 deg BTDC. The Intake Camshafts at 114 deg ATDC may actually retard to 113 deg ATDC.

b. Fixed Timing Chain Guide wear.

As the Fixed Timing Chain Guides wear the chain returning to the Idler Sprocket between the Camshaft Sprockets and Idler Sprocket decreases in effective length Advancing the Intake Camshafts and retarding the Exhaust camshafts. The Exhaust Camshaft may retard from 110 deg BTDC to 109 deg BTDC. The Intake Camshafts may Advance from 114 deg ATDC to 115 deg ATDC.

Last UPDATE of post 24 Aug , 2017

LT5 Timing Chains and Sprockets
 

LT5 Timing Chains and Sprockets

See Timing Chain Idler Sprocket Lubrication and Installation

1. Background Timing Chain Sprockets and Lubrication within front cover.

A #20 Torx can be used to remove the small Torx screw holding the bearing cover in place on the Timing Chain Idler Sprocket. Place two of the Timing Chain Idler Sprocket bolts (10 mm Head x 8 mm x 100 mm) into the Idler Sprocket holes with the Heads of those two bolts in a vice. Remove the #20 Torx screw. Use Red Loctite when replacing the #20 Torx screw.

There is an oil path around one of the three 10 mm Head (8 mm) x 100 mm bolts that attaches the inner race of the Timing Chain Idler Sprocket to the engine case (The distance between two 8 mm x 100 mm bolts is smaller so the Timing Chain Idler Sprocket inner race can only be attached to the engine case one way).

This oil path is vented from the bolt hole into the needle bearing area of the inner race. The Timing Chain Idler Sprocket inner race can be attached to the engine case in only one orientation assuring that the oil pressure from the engine case is directed to the Timing Chain Idler Sprocket Bolt hole that is vented to the needle bearings..

https://cimg7.ibsrv.net/gimg/www.cor...f81e0ce8d6.jpg
https://cimg9.ibsrv.net/gimg/www.cor...318f8f1687.jpghttps://cimg0.ibsrv.net/gimg/www.cor...e71cdb3cf5.jpg

The two sets of Timing Chain Idler Sprocket needle bearings can be seen in the photos.

https://cimg1.ibsrv.net/gimg/www.cor...b71e81c6cd.jpghttps://cimg3.ibsrv.net/gimg/www.cor...dc796e4f1a.jpg

The Timing Chain Idler Sprocket oil pathway entrance to needle bearings from bolt hole to the inner race (left) and exit from sprocket (right) can be seen in the small ports of the inner race and outer sprockets.

https://cimg4.ibsrv.net/gimg/www.cor...59b98024ea.jpghttps://cimg5.ibsrv.net/gimg/www.cor...273451e046.jpg

2. LT5 Timing Chain Calculations.

Timing chain breakage although very rare has been blamed on repeated engine pulses or fatigue (dead injector or bad valves for example). The timing chain calculations in this post debunk all such theories on timing chain failure.
http://www.f-lohmueller.de/pov_tut/a...Chain_35tt.gif

LT5 Cranskshaft sprocket has 20 teeth.
LT5 Idler sprocket on primary side has 42 teeth
LT5 Idler sprocket on secondary side has 21 teeth
Each LT5 camshaft sprocket has 20 teeth
LT5 Primary chain has 54 pins
LT5 Secondary chain on LH has 102 pins
L T5 Secondary chain on RH has 94 pins

So...we know the camshaft sprockets rotate half as fast as the crankshaft sprocket.

Lets calculate......Crankshaft sprocket rotates 360 deg or 20 teeth. Idler sprocket primary rotates 20/42 of 360 deg or 20 teeth. Idler sprocket on secondary side rotates 20/42 of 360 deg or 10 teeth. Camshaft sprocket rotates 180 deg or 10 teeth. Exactly 180 deg like it is suppose to.

Now lets see how much of total length the RH and LH secondary chains rotate. Crankshaft sprocket rotated 20 teeth or 360 degrees. Primary chain has 54 pins so it rotated 20/54ths of its length. Camshaft sprocket rotated 180 deg or 10 teeth so for RH chain with 94 pins that is 10/94ths of its length and for LH chain with 102 pins that is 10/102nds of its length.

Lets put this another way.......each time the crankshaft sprocket rotates 360 degees, the RH chain moves 10/94ths of its length and the LH chain moves 10/102nds of its length. Or if the RH chain were to rotate its full length, the crankshaft sprocket would rotate 9.4 times and if the LH chain were to rotate its full length, the crankshaft sprocket would rotate 10.2 times.

Now...let us look at the analysis in above posts wherein a miss fire could cause chain failure.

The bad cylinder miss fires once every two revolutions of the crankshaft. That little tug on the chain would occur on the RH chain 4.7 times as it rotated its full length. That little tug would occur on the LH chain 5.1 times as it rotated its full length. And the little tug from a bad injector would occur at different locations on each chain every revolution of the crankshaft since these (4.7 and 5.1) are not whole numbers.

Primary drive crankshaft sprocket................................Primary chain

https://cimg6.ibsrv.net/gimg/www.cor...b813bcb091.jpghttps://cimg7.ibsrv.net/gimg/www.cor...ccc2faeaf2.jpg

Idler sprocket........................................ ...........Secondary chain (LH top, RH bottm)

https://cimg8.ibsrv.net/gimg/www.cor...4a195dc4b9.jpghttps://cimg0.ibsrv.net/gimg/www.cor...4f15e298f3.jpg

One of four camshaft sprockets

https://cimg2.ibsrv.net/gimg/www.cor...1e67cf5908.jpg

Last UPDATE of post 25 Aug, 2017

Setting/Installing the Chain Tensioners Tricks
 

Setting/Installing the Chain Tensioners Tricks

Start with Ben's RH Tensioner photo on how to reset chain tensioner (The RH and LH Tensioner are different).

https://cimg3.ibsrv.net/gimg/www.cor...cf0c56ef0a.jpg

1. Resetting the Chain Tensioner.
a. A is the Transport Clip which is smaller than B (the operational clip).
b. Leave A in the groove on the left end of the plunger and move B to the smaller width reset groove just left of the wider operational groove.
c. Place the spring inside the plunger and insert the plunger with spring into the Tensioner Housing.
d. Place the Tensioner with plunger inserted in a vice being carefull not to mark the plunger tip (left end of plunger) with the jaws of the vice. The plunger tip should be exposed so a knife edge can be inserted in the end of the tensioner housing to move Transport Clip A when the plunger is fully compressed within the tensioner housing.
e. With the plunger compressed into the tensioner housing (with Transport Clip A in the groove on the left end of the plunger), insert the knife blade and move any part of the Transport Clip A further into the tensioner housing out of the groove on the left end of the plunger.
f. Hold the Transport Clip A (any part of the Transport Clip) out of the groove on the left end of the plunger when you gradually open the vice.
g. If you start to see the Transport Clip A, it did not catch the inside of the Tensioner Housing for transport. Recompress the plunger inside the Tensioner Housing and move any part of the Tansport Clip A one more time out of the initial groove. Gradually open the vice and you will see the plunger is now caught inside the Tensioner Housing. The Chain Tensioner is now SET for Transport.

2. Activating the Chain Tensioner.
a. Rotate the crankshaft clockwise looking at the front of the engine. This will loosen the timing chain on the tensioner side of the timing chain sprockets. This will allow the tensioner to extend maximum length when the tensioner is unset in step 3 below.
b. Insert the chain tensioners (Plunger set for transport) into the locator housings that will be bolted to the heads (chain tensioner lubricated with engine oil and installed into locator housing).
c. Make sure the "O" rings are in place on the locator housing and that the "O" rings stay in the grooves of the locator housing (a bit of permatex sealant on the "O" ring will hold it in place). Tighten the two bolts of the RH and LH locator housnigs to the RH and LH heads.
d. Make sure both left and right chain tensioner slots are alligned vertically so they allign with the left and right chain guides.
e. Make sure that the oil ports of the tensioner locator housing is facing up with tensioner locator housing installed in the heads. The LH and RH locator housings are different in regard to oil port and bolt alignment (RH bolts are vertical, and LH bolts are horizontal).
f. Remove allen head plug on the tensioner locator housing.
g. Insert a small punch positioned through the hole (removed allen head plug) on the top of the tensioner locator housing. Tilt the punch to the side making sure you are not punching the check valve on top of the barrel of the tensioner plunger. Give the punch a sharp tap with a small hammer. This unsets the chain tensioner plunger from the transport position in the tensioner housing moving the Transport Clip A back into its original groove on the tip of the plunger.
h. Install the allen head plugs in the RH and LH tensioner locator housings with blue loctite.

Unset LH chain tensioner..........................Unset/set RH chain tensioner (Photo by Craig)

https://cimg6.ibsrv.net/gimg/www.cor...f8df145df1.jpghttps://cimg7.ibsrv.net/gimg/www.cor...46e8fee475.jpg

Last UPDATE of post 26 Aug, 2017

Cam Cover Installation Tricks
 

Cam Cover Installation Tricks

Drivers Side Cams........................................ ........Passenger Side Cams

https://cimg9.ibsrv.net/gimg/www.cor...1b299a2fa9.jpghttps://cimg0.ibsrv.net/gimg/www.cor...b3a6ea6429.jpg

1. Insert spark plugs with a bit of anti-sieze on the threads before installing the Cam Covers to assure that nothing drops into the cylinders.
2. Leave Jeffvette Billet Aluminum Camshaft Retainers in place as the cam cover journals will take the camshaft loads once the cam covers are in place. The Camshaft Billet Aluminum Retainers do prevent the camshaft longitudinal movement however.

https://cimg1.ibsrv.net/gimg/www.cor...a5f2b41787.jpghttps://cimg2.ibsrv.net/gimg/www.cor...76781904a4.jpg

a. Use Loctite 518 (Permabond A136 recommended from Jerrys Gaskets) very thin coat on surface of cam covers. Do not coat 518 Loctite all the way to the edge of the journals (stay away 1/4 inch). leave 1/8 inch more or less space between Loctite 518 and outer/inner edges of any surface coated. Also, do not coat the cam covers all the way to the outer and inner edges (leave 1/8 inch more or less space between Loctite 518 and outer/inner edges of any surface coated). (Coat the grooves for the two camshaft rubber plugs on each end of each Cam Cover and same on each end of each head.

https://cimg6.ibsrv.net/gimg/www.cor...44606a29b9.jpg

b. Lubricate all cam lobes and lifters with engine oil but do not get any oil on the Cam Cover interface surfaces.
c. Place spark plug "O" rings in place and on the Cam Cover place a thin coat of 518 Loctite around each spark plug hole.
d. On all surfaces keep thin coat of 518 Loctite 1/8 inch from edges of each/every surface.
e. Set Cam Covers in place on Heads.
f. Insert 24 SS Allen Head 8 mm (Replace original Torx-40....See....Post 67 - Removing Cam Covers (Engine In Car) for Inspections of Camshafts) 3 SS Allen Head 6 mm Cam Cover bolts with Aluminum Stat-O-Seal Washers (Do not use Loctite or Anti-sieze on Cam Cover bolts). I also used eight 1/4 inch Aluminum Stat-O-Seals for the IH coolant housings. The Aluminum Stat-O-Seals make a great lock washer as well as prevent oil leaks around the SS bolts.

https://cimg7.ibsrv.net/gimg/www.cor...aec3c63a23.jpg

Pegasus Auto Racing (Check Jerrys Gaskets for latest Stat-O Seal type Washers)

3. Tightgen all cam cover SS bolts in several steps
a. Tighten All Cam Cover bolts using a #6 Allen Head wrench including the 3 #4 Allen Head bolts on the front edge of each Cam Cover.
b. Check that the crankshaft is still free to rotate during and after tightening Cam Cover bolts.
c. Clean any excess 518 loctite from cam covers.

4. Cam Inspection after several hours Run In
a. Drivers side Cam Cover was removed after several hours of engine time after installation of regrind camshafts. The Cams and Cam Journals were found to be in perfect condition with no unusual wear marks.
b. The Billet Camshaft Retainers were found to be in perfect condition with all bolts tight.
c. The Lubrication condition was found to be perfect with all Cams and Lifters fully lubricated.

Last UPDATE of post 27 Nov, 2019

PCV system (Need for Oil Catch Can)
 

PCV system (Need for Oil Catch Can)

See Cam Covers (Filters and Wear Strips) For Discussion of Cam Cover Wear Strips.

The PCV system with the dual PCV valves (each with its own vacuum characteristic) in conjunction with an Oil Catch Can evacuates the crankcase. See Elite Oil Catch Can Installation Details.

Oily gasses traveling upwards from the Crankcase Ventilation Cover bring oil into the IH which two small holes (each IH) let that oil drain back into the Head (The 90' being a bit different than the 91' in that regard with respect to oil drain hole sizes). From the IH the gasses are sucked through the PCV valves from each side of the IHs through two hard lines.

It is assumed that oil in the camshaft area drains back down into the crankcase through relatively small drain holes in the Heads. The area under the Cam Covers is then at the same pressure (depending on the capacity of the oil drain holes in the heads to pass gasses the opposite direction into the Camshaft area) as the Crankcase (compression gasses passing past rings).

The vacuum in the PCV return line and the Cam Cover Vents are a bit different as the Cam Cover vent line is attached to the Air Horn and the PCV return line is attached to the Plenum behind the Throttle Body. That means at idle you get a lot of vacuum pulling on the dual PCV valves and almost zero pulling on Cam Cover vents. At Wide Open Throttle (WOT) you get about equal vacuum on both maybe.

So.....you are pulling most oil through the Cam Cover Filters l at WOT and if you have a clogged air filter you are pulling even more vacuum at WOT from the Cam Cover vents but that is prolly just not a factor. Now if the Cam Cover Filter is clogged up, you might have a positive crankcase pressure since there is not much vacuum on the PCV system. The crankcase pressure would be greatest at WOT with the most gasses escaping into the crankcase around the rings.

In the case of a positive crankcase pressure you might see oil around the Cam Covers. Just guessing here to determine what can be done if the Cam Cover Filtersl get clogged up Cam Cover Filters

It seems that the Crankcase pressure would be totally dependent on the condition of the rings. PCV valves, and Cam Cover Filters. The amount of gas passing through the PCV system and Cam Cover Vents is equal to the amount of gas passing past the rings at all times.

I switched from Scotch Brite to Marc Haibeck's new Cam Cover Vent filter material Cam Cover Filters

https://cimg8.ibsrv.net/gimg/www.cor...27b9fca183.jpg

Last UPDATE of post 28 Aug, 2017

Plenum Pull (1990 ZR-1)
 

Plenum Pull
1. Just make sure you drain enough coolant if you do not have Throttle Body Coolant Blocked.

2. Electrical Connections associated with Plenum Pull (1990 ZR-1)
The 4 connectors on the Distributorless Ignition System (DIS) under the plenum are not interchangeable. The 2 Connectors towards the front of the DIS carry the coil primary controls signal. The small one at the back of the DIS is switched B+. The big one carries ECM signals.
a. Disconnect two larger electrical plugs under front of DIS to underside of DIS from front of plenum.
b. Disconnect the smaller electrical plug and ECM signal plug (1/4 inch socket with short extension) under rear of DIS from rear of plenum.

3. Tools
a. Used a 1/4 inch socket wrench with short extension and 1/4 inch socket to install the bolt in the DIS module electrical connection from rear of plenum with plenum up 3 inches (DIS attached under the Plenum).
b. Used a 3/8 inch socket wrench with 6 mm allen heads for plenum SS bolts.

https://cimg6.ibsrv.net/gimg/www.cor...2d2ecd7fd2.jpghttps://cimg7.ibsrv.net/gimg/www.cor...bf23787e4e.jpg

Two Allen Head wrenches (6mm and 3mm),
Two flat head Screw drivers and ...................................1/4 inch socket wrench with 1/4 inch socket
TB bracket wrenches (7mm and 9mm)..........................and short extension for DIS Connector
https://cimg2.ibsrv.net/gimg/www.cor...855b7551a6.jpghttps://cimg3.ibsrv.net/gimg/www.cor...cfd256ba1a.jpg

4. The 10 Minute Plenum Removal (1991 LT5 after Eliminated TB Coolant, Installation of Oil Catch Can and Installation of SS Allen Head Bolts).

TB Coolant Elimination is Item #4 LT5 Eliminated Systems

B. Plenum Removal Steps (assuming you have TB Coolant Blocked). If not.....remove some coolant before you start.
1. Disconnect Battery (Check Battery Condition and Jumper GOOD Battery as FIRST CHECK).
2. Remove Samco (or stock) Air Duct (large flat screw driver).
3. Remove Oil Catch Can Hose (If Oil Catch Can Installed) to Plenum and PCV Dual Connector on back of Plenum (small flat screw driver).
4. Remove Throttle Body Cables (two including TB Shield and two top (I have 3mm SS Allen Head) screws on Plenum) and TB Connector (7mm and 9mm wrenches).
5. Remove Fuel Regulator Vacuum Hose "L" rear of Plenum.
6. Disconnect MAP Vacuum hose from MAP (Manifold Absolute Pressure) and from rear of Plenum.......
(in case it gets intangled with other wires/hoses I just disconnect MAP bracket from Plenum).
7. Disconnect Passenger Side Plenum Vacuum (and Drivers side Plenum Vacuum if secondaries not removed).
8. Disconnect Brake Boost Vacuum line Drivers Side Rear of Plenum.
9. Remove three 6mm Allen Head SS Fuel Line Bolts and two fuel lines (6mm Allen Ball Head Socket) or Torx-40 stock bolts.
10. Open gas cap to prevent fuel lines from leaking when removed from fuel rail.
11. Remove 12 Allen Head SS Plenum Bolts (6mm Allen Ball Head Socket with Extension) or Torx-40 stock bolts.
12. Lift Plenum from Gasket (front only) and remove two Cam Cover PCV Vent Rubber Connectors to Air Horn.
13. Disconnect two DIS (Distributorless Ignition System) Connectors front of DIS.
14a. Disconnect large Purge Vacuum line under front of Plenum (91').
14b. Disconnect small vacuum line under front of Plenum and larger vacuum line from drivers side of Plenum going to Charcoal Canister under left head light (90').
15. Disconnect two small electrical connectors rear under Plenum (MAP and DIS).
16. Unscrew 1/4 bolt in Main DIS Connector rear of Plenum.
17. Remove Plenum.

Last UPDATE of post 29 Mar, 2018

LT5 IH (RC Injectors), Fuel Rails, Plenum Install Tricks
 

LT5 IH (RC Injectors), Fuel Rails, Plenum Install Tricks

I use RC SL4-205 injectors (500+ hp). Tech Info - LT5 RC SL4-205 injectors (500+ hp) Calculations
The RC Secondary come with Blue Caps covering the "O" ring. The Blue Caps must be removed before installing the RC Secondary Injectors.

1. After removing Plenum use high pressure Air Pressure to clean all debris around Injectors before removing the Injectors.

2. Fuel Rail Removal.
a. There are 4 bolts that hold the fuel rail in place...remove them.
b. Disconnect the fuel lines at rear of fuel rail (there are "O" rings).
c. Disconnect the electrical to each injector (spring loaded clip).
d. Wiggle the fuel rails with upward pressure popping the injectors out of the Injector Housing.
e. The Purge vac line is on top as well as Cruize control vac line on passenger side and Aux secondary vacuum on drivers side.
f. Remove the clips holding each injector on fuel rail and pull injectors out of fuel rail.

3. Installation of New Injectors.

Remove the protective blue plastic cape protecting the secondary
injector "O" ring before installing into the Injector Housing.
https://cimg9.ibsrv.net/gimg/www.cor...1351ee44be.jpg

4. "O" Rings in IH and on Injectors......Primary LEFT ("O" Ring in IH) and Secondary RIGHT ("O" Ring on Injector)
Used just a tad of white grease on the "O" rings (Primary and Secondary Injectors) for easy installation of injectors.

https://cimg5.ibsrv.net/gimg/www.cor...676e49f4fd.jpg

5. Bracket install Trick (Purge connector through rear drivers side runners of Plenum).
a. Modified bracket on passenger side of Plenum for Purge connector which was attached to TB coolant return (since removed).
b. Kept the bracket and reinstalled bracket on passenger side of Plenum (second bolt from fire wall) for Purge connector.
c. The TB return line to coolant tank in front of passenger side windshield has been capped off with brass plug.

6. Tools.
a. Used a 1/4 inch socket wrench with short extension and 1/4 inch socket to install the bolt in the DIS module electrical connection from rear of plenum with plenum up 3 inches (DIS attached under the Plenum).
b. Used a 3/8 inch socket wrench with 6 mm allen heads for plenum SS bolts.

https://cimg6.ibsrv.net/gimg/www.cor...2d2ecd7fd2.jpghttps://cimg7.ibsrv.net/gimg/www.cor...bf23787e4e.jpg

7. Electrical Connections associated with Plenum Pull (1990-1991).
The 4 connectors on the Distributorless Ignition System (DIS) under the plenum are not interchangeable. The 2 Connectors towards the front of the DIS carry the coil primary controls signal. The small one at the back of the DIS is switched B+. The big one carries ECM signals.

a. Attach two larger electrical plugs under front of DIS to underside of DIS from front of plenum.
b. Attach the smaller electrical plug and ECM signal plug (1/4 inch socket with short extension) under rear of DIS from rear of plenum.

8. Engraving Tricks.
Thanks to Carter for the great engraving on coolant manifolds and TB plate :thumbs:

https://cimg5.ibsrv.net/gimg/www.cor...ce3c549ef9.jpg

Last UPDATE of post 30 Mar, 2018

Vacuum Systems 90' and 91' (Secondary and Cruize/HVAC)
 

Vacuum Systems 90' and 91' (Secondary and Cruize/HVAC)

1. Secondary Vacuum System
The first photo shows details of the vacuum plumbing around the Secondary Vacuum Solenoid and Secondary Vacuum Reservoir Including the Check Valve. The second photo is the complete Secondary Vacuum System.

The Check Valve allows plenum vacuum to be seen by Secondary Vacuum Reservoir but does not allow plenum to see Vacuum pump vacuum.

https://cimg6.ibsrv.net/gimg/www.cor...7b346ad742.jpg
https://cimg8.ibsrv.net/gimg/www.cor...f285cb9d6c.jpg

2. Cruize Control and HVAC
The vacuum line on the passenger side of the plenum is for the cruise control and HVAC. That vacuum is a separate system.

The cruize control and HVAC Vacuum are NOT eliminated having nothing to do with the secondary vacuum system removal. See item #3 LT5 Eliminated Systems

The cruize control plenum vacuum line (mid plenum connection passenger side) and L connector is shown on left and Cruize control is shown on right. A vacuum line is connected to one of the connections shown left photo (L connector) running forward under plenum (out front of plenum) to drivers side wheel well. There it connects to a connector going forward to vacuum reservoir under drivers side head light (bottom photo) and backward to Cruize Control shown in right photo just above battery on drivers side. The other vacuum hose connected to the Cruize Control is for the brake pedal cruise cancel function.

The second connection shown in left photo (L connector) connects to the HVAC vacuum line included in passenger side fuel injector wire harness.

https://cimg1.ibsrv.net/gimg/www.cor...c9244e4ee1.jpghttps://cimg2.ibsrv.net/gimg/www.cor...d74ad6c89d.jpg
https://cimg4.ibsrv.net/gimg/www.cor...97e78ab896.jpg

3. Differences between 90' and 91' Vacuum Systems
See Vacuum Systems (90' & 91') TIPS

See Differences between 90', 91' and 95' Crate Engine Plenums and IHs
Note Vapor Canister Control Valve Vacuum differences.

90' Vacuum System

https://cimg5.ibsrv.net/gimg/www.cor...297bbca2dc.jpg

91' Vacuum System

https://cimg6.ibsrv.net/gimg/www.cor...b1ad0987ed.jpg

4. Checking Vacuum System.
Before you tighten down the Plenum (with Plenum tipped up in front) and ALL vacuum lines, and DIS module connections in place....check your vacuum systems.

With all vacuum lines connected, turn key on and listen for vacuum pump to shut off. If it does not shut off, start at the closest vacuum line to the vacuum pump disconnecting the line and holding your finger over the end. If the pump shuts off the leak is on other side of that. Go to next fitting and do the same until you are past the leak wherein the vacuum pump will NOT shut off. You have now located the leak.

If the Plenum has NOT been removed Check between Vacuum Pump and Plenum first....then check Drivers side Plenum Vacuum Connection to see if the Check Valve under Plenum is leaking. Disconnect that vacuum fitting and hold finger over end of vacuum line to see if pump stops cycling...if pump stops cycling the Check Valve is leaking.

Also check your HVAC and Cruize Control Vacuum System (check ALL connections). Also check your EVAP Purge system connections (charcoal canister which is under drivers side headlight on your 90'). That single small vacuum port under front of plenum facing rearward (90' only) is for the Evap Purge System. The second larger vacuum port on drivers side lower front of plenum is the main vacuum line for the Charcoal Canister. The second Vacuum port right next to that Charcoal Canister port is your PCV Vacuum port.

With the key on, ground the pink wire in the green connector (third from drivers side) on ECM. Use a small finishing nail stuck in alongside the wire connector with an alligator clip pigtail attached to the end for grounding. This will activate the Secondaries which you can watch with the plenum tipped up in front before you bolt it down. This after you are sure you have NO vacuum leaks in the Secondary System.

Last UPDATE of post 31 Dec, 2017

Eliminating IH Housing Throttle Body (TB) Coolant system
 

Eliminating IH Housing Throttle Body (TB) Coolant system.

Install 1/8 inch NPT allen head pipe plugs (21/64 or 11/32 drill) two each side of Plenum (Two each TB Coolant and Injector Housing (IH) Coolant) as shown (The associated two IH coolant ports in the IH can also be plugged on each side).

See Summit Racing for Aluminum Pipe Plugs.

Remove hose and tubing left and right side of plenum, plug hose return to coolant tank passenger side. See item #9 TB Coolant Return Modified. Initial Coolant Fill may be somewhat affected by the TB Coolant Elimination (see item #4 Initial Coolant Fill).

https://cimg7.ibsrv.net/gimg/www.cor...0c37de3bc7.jpg

Note: The TB coolant path back to the passenger side overflow tank does provide a path for air and potential air lock to return to that passenger side tank during initial coolant fill. However, the Plenum to TB coolant hose sits only an inch or so above the IH coolant manifolds on the passenger side so the benefit of using that path to bleed air vice the top of the coolant manifolds to the radiator is very small. Marc has decided to bypass the TB coolant (vice eliminate all TB coolant hoses) leaving that coolant path back to the passenger side overflow tank in place to assure issues would not arrise on rebuilds for those unaware of coolant initial filling and water pump potential air locks.I also park on KwikLift sloped upward which assures IH coolant manifolds are voided of air at all times (especially if engine is reved a bit).

The 5th plug (Plenum Vacuum) is for Plenum Vacuum drivers side only which was connected to the vacuum reservoir. The tubing can be removed and a 1/8 inch NPT allen head pipe plug inserted exactly like the plenum coolant plugs.

a. When you run the tap....keep checking the pipe plug for depth so you end up tight and flush.
b. When you run the Drill.......remember you are in ALUMINUM so go very easy and slow!!! (you can do it without a drill press).
c. Use a bit of Permatex gasket sealer or Teflon tape on the pipe plugs.

See this link for TB Coolant Blocking drilling and threading details Injector Housing TB Coolant Blocking



https://cimg9.ibsrv.net/gimg/www.cor...26ca673361.jpg
see item #4 TB Coolant Eliminated.

https://cimg7.ibsrv.net/gimg/www.cor...0c37de3bc7.jpg

Last UPDATE of post 32 Dec, 2017

Eliminating Secondary Throttles/shafts
 

Eliminating Secondary Throttles/shafts.

Install Dorman freeze plugs 555-108 with Loctite 262 to plug the secondary shaft ports for a complete elimination of Secondary throttle shafts and associated vacuum canisters. Summit Racing Freeze Plugs 555-108

https://cimg1.ibsrv.net/gimg/www.cor...21ef57f654.jpg

Removing Secondary Shafts Engine In Car TIPS

Last UPDATE of post 33 Jan, 2017

Stainless Steel Air Box and Air Filter (L98 and LT5)
 

Stainless Steel Air Box and Air Filter (L98 and LT5)

The Stainless Steel Air Box has been offered for those that want to add Bling and Higher Intake Air Flow for the LT5 or L98 :thumbs:

1. SS Air Box Installation and Air Filter Selection

George Braml fabricates the SS Air Box.

Just an installation tip....If you use that Orange FRAM Air Filter you will find it about 1/4 inch too high. The bottom end of the SS Air Box Square Filter Retainer lip will not engage the Built In (L) of the Air Box at the bottom end as shown in the first photo (the Orange Fram Air Filter has a gap at the bottom end). You will also notice the two Retaining screws for the Square SS Air Box Filter Retainer have tilted towards the engine indicating the top Square Retainer has moved upward out of the SS Air Box (L) at the bottom end.

If you look closely at the SS Air Box Square Filter Retainer you will see a cut out about 1/4 inch deep and the width of the Square Filter Retainer on the bottom end. The height of the Air Filter cannot be higher than that cut out (The Orange Fram Filter is about 1/4 inch higher than that cut out).

The K&N 33-2035 High Flow Air Filter is the correct Air Filter matching the SS Air Box Cut Out.

George Braml did a perfect fabrication job on the L98 SS Air Box as he did on the LT5 SS Air Box (Both SS Air Boxes are IDENTICAL) :thumbs:

2. Facts and Photos

The L98 and LT5 SS Air Box and Air Filters are Identical.

A. The Air Filter opening is 9.5 in x 16.25 in or 154 square inches (both OEM and SS).
B. The Air path inside the Air Filter housing to the oval outlet is 1 in x 17.25 in or 17.25 square inches (both OEM and SS).
C. The OEM metal cover Louvers are 3/8 in x 4 in or 1.5 square inches and there are 24 Louvers or 36 square inches for Air Flow into the Air Filter area (OEM only).
D. Space between top of OEM metal Louvered cover and closed hood exceeds 1 inch all around (more space with SS Air box since metal louvered cover is not used.
C. Using SS Air Box with FRAM decreases the space between top of Air Filter and closed hood by 1/4 inch or 12.5 square inches around the perimeter of the Air Filter.
D. Using the SS Air Box with K&N High Flow Air Filter eliminates the need for the OEM metal Air Box cover (36 inches of air flow area) making available the total air flow area of 154 square inches to the K&N 33-2035 High Flow Air Filter.
E. The K&N 33-2035 High Flow Air Filter is Washable and Reusable.

A. K&N 33-2035 High Flow Air Filter

B. K&N 33-2035 High Flow Air Filter

SS Air Box installed with FRAM Air Filter with bottom of Filter Square Retainer not engaged
https://cimg2.ibsrv.net/gimg/www.cor...f518301731.jpg

SS Air Box and OEM Air Box bottom compared showing where they ride on ridge
of radiator shroud (SS Air Box) and between ridges of radiator shroud (OEM Air Box)
http://https://cimg3.ibsrv.net/gimg/...4815d81f37.jpg

SS Air Box and OEM Air Box bottom compared showing where they ride on ridge
of radiator shroud (SS Air Box) and between ridges of radiator shroud (OEM Air Box) close up
https://cimg7.ibsrv.net/gimg/www.cor...6d171a0644.jpg

SS Air Box installed showing 1/4 inch Cut Out on lower side of Square Air Filter Retainer
with K&N High Flow Air Filter fitting under small cross member
https://cimg9.ibsrv.net/gimg/www.cor...b583ac428d.jpg

OEM Air Box with metal Louver cover
https://cimg1.ibsrv.net/gimg/www.cor...f8fb21a59f.jpg

FRAM Air Filter exceedes the SS Air Box Square Retainer 1/4 inch cut out height
(filter shown above SS metal)
https://cimg2.ibsrv.net/gimg/www.cor...1301482ff5.jpg

K&N 33-2035 correctly sits even with the 1/4 inch cut out
https://cimg3.ibsrv.net/gimg/www.cor...b521119500.jpg

For the installation of the K&N 33-2035 air filter in the "stock" Air Filter Housing......SEE

Post 276 - Air Filter Installation

3. Technical Discussion
The air is drawn from top side of Air Filter in the OEM set up through the louvers in the metal cover. There is a gap of at least an inch between that Air Filter metal cover and closed hood (OEM or SS Air Box).

With the SS Air Filter housing, there is NO metal cover and air is drawn from air gap between the filter and closed hood not restricted by the 36 square inch Louver area of the OEM Metal cover. With a K&N High Flow Air Filter that gap is 1/4 inch larger (than when using a FRAM Air Filter).

The OEM filter housing metal cover will accomodate both FRAM and K&N 33-2035 Air Filters. The difference between the SS Air Box and OEM Air Box is that the SS Air box rides a bit higher requiring the 1/4 inch Cut Out for the small front crossover (see photos of the bottom of both the OEM and SS Air Box.

Because of the Cut Out the SS Air Filter housing with correct K&N 33-2035 High Flow Air Filter will sit at the same height as an OEM Air Box. However if you use a higher FRAM Air Filter that exceedes the Cut Out height in the SS Square Retainer, the overall height of the top of the filter has changed and will interfere with the front small corss over. This will in turn cause interference bwtween the FRAM Air Filter and small cross over preventing the Top Square Retainer of the SS Air Box from engaging at the bottom end.

The L98 and LT5 are IDENTICAL in regard to these issues as the OEM Air Filter housings are IDENTICAL and the radiator shrouds appear to be IDENTICAL in regard to top side of that shroud.

A. K&N 33-2035 High Flow Air Filter

B. K&N 33-2035 High Flow Air Filter

https://cimg6.ibsrv.net/gimg/www.cor...01510033e9.jpg

4. Water Deflector
The Water Deflector which sits under the end of the OEM Air Box (or SS Air Box) to prevent water from being sucked into the Air Intake from the front grille. What it also does is prevent cooler air from entering the Air Intake from the grille. I deleted the Water Deflector from both the L98 and LT5 SS Air Box installations.

https://cimg7.ibsrv.net/gimg/www.cor...032d71389a.jpg

5. Powder Coating or Painting SS Air Box
I did not Powder Coat or Paint the SS Air Box as it looks very very nice as a SS Machined look and the welding is absolutly perfect......so why cover up with Powder Coating or Paint :cheers:

https://cimg0.ibsrv.net/gimg/www.cor...1f5325bf66.jpg

Last UPDATE of post 34 Sep, 2022

Pilot Bearing and Clutch Operation
 

Pilot Bearing and Clutch Operation

1. Pilot Bearing
Two issues important in the clutch area are the replacement of the throwout bearing and Pilot Bushnig/Bearing. There has been much confusion over which Pilot Bushing/Bearing is to be used. GM has changed their part numbers several times and are currently referring to the bearing (part #14061685) to be used.

It has been suggrested to NOT use this bearing as it is a needle type bearing designed for 6.2L diesel trucks which have a limit of only 4,000-4,500 rpms. The theory is that those little needles will turn at over 7,000 rpms. It has therefore been suggested the ideal bushing replacement is a bronze type with three grooves (or flutes) spiraled inside and is available under the GM part number 10125896.

This really only applies to drag racing where you drop the clutch at high rpms. At all other times the RELATIVE rpm difference between the transmission spline and the flywheel are low and much less than 4,000 rpm. The needle bearing pilot would be the best choice for most applications excluding drag racing.

Matter of fact except when starting out in first gear engaging the clutch a bit above idle rpm, one trys to match transmission spline rpm with engine/flywheel rpm when selecting higher or lower gears. This method of shifting gears is also much better for the syncros (Depress the clutch, take it out of gear, syncronize rpms between the flywheel and transmission spline in the gear to be selected, and then shift to higher or lower gear, release clutch).

I use the Needle Type Pilot Bearing :thumbs:

2. Pilot Bearing Depth

All measurements from the surface of the rear of the crankshaft (bottom arrow).
The depth to the plug is 34.90 mm (top arrow).
The depth to the raised bottom of the pilot hole is 31.75 mm (Second arrow from top).
The depth to the raised portion of the pilot hole (the pilot bearing housing in the crankshaft) is 9.5 mm (third arrow from top).
The height of the Roller Bearing (width of outer race) is 17.45 mm.

So......I am assuming the new roller bearing pilot should be sunk in past the raised portion of the housing (third arrow from top) about 4.5 mm or .175 inches.
In other words just a bit past the raised portion of the pilot bearing hole. This would put the other end of the pilot bearing almost exactly to the raised portion near the bottom of the pilot hole at 31.75 mm (second arrow from top).

Using a Blind Hole Slide Hammer to easily pull the old Pilot Bushing.
https://cimg2.ibsrv.net/gimg/www.cor...af9cc81217.jpghttps://cimg0.ibsrv.net/gimg/www.cor...a570a22341.jpg

The height of the Roller Bearing is 11/16 in (17.45 mm) ....... The face of the Bronze Pilot Bushing I removed
........................................ ........................................ ...............was even with the reduced diameter of the bore.
https://cimg3.ibsrv.net/gimg/www.cor...319cf62b33.jpghttps://cimg4.ibsrv.net/gimg/www.cor...272be863d1.jpg

3. Dimensions of Black Label Transmission which except for Throwout Bearing Inside Diameter are identical to Blue Label Transmission.

https://cimg7.ibsrv.net/gimg/www.cor...f4e1ff2bcc.jpg

1 inch or 25.4 mm........................................ ................................1.373 inch or 34.87 mm
https://cimg8.ibsrv.net/gimg/www.cor...3ae46e8181.jpghttps://cimg0.ibsrv.net/gimg/www.cor...d3753b7598.jpg

7.50 inches or 190 mm
https://cimg1.ibsrv.net/gimg/www.cor...fb173b6336.jpg

Throwout Bearings and Clutch Forks

4. Clutch Fork
The Clutch Fork pivots on a pivot post attached to the Bell Housing. The outer part of the Clutch Fork lever is pushed in by the rod of the Clutch Slave Cylinder.

Inside the Bell Housing Left and Outside the Bell Housing Right. You can see in the Left Photo that the Clutch Fork can be slipped to the Right off the pivot when positioning the Bell housing on the engine so the Clutch Fork Fingers can be positioned on the Throwout Bearing during installation of the Bell Housing.

https://cimg2.ibsrv.net/gimg/www.cor...06bbb0d0f2.jpghttps://cimg3.ibsrv.net/gimg/www.cor...4391f4d50e.jpg

5. Throwout Bearing
The throwout bearing is locked inside the pressure plate fingers with a circular wire clip. The Throwout Bearing is inserted inside the pressure plate before the pressure plate and clutch disk are attached to the fly wheel.

When the outer part of the Clutch Fork lever is pushed in by the rod of the Clutch Slave Cylinder, the other end of the Clutch Fork is pulled away from the center of the Pressure Plate. The Fingers of the Clutch Fork engage the corners of the throwout bearing square collar and pulls the throwout bearing out and away from the clutch surface (Center Force Clutch/Pressure Plate shown). This assembly shows a Blue Label Throwout bearing as a 95' ZF S6 40 Transmisison was used with a 91' engine.

https://cimg4.ibsrv.net/gimg/www.cor...c4c29b6b3e.jpghttps://cimg6.ibsrv.net/gimg/www.cor...34d8fbdf90.jpg

The throwout bearing pulls the Pressure Plate Fingers which each finger has a pivot point at the outer edge of the pressure plate with an attachment to the pressure plate at approximately the half way point to the outer edge. This pulls the pressure plate surface away from the clutch disk releasing the clutch.

The outer part of the throwout bearing is always rotating with the clutch (engaged or not). The inner part of the throwout bearing does not rotate but is lubricated to slide in and out on the outer collar of the transmission input shaft.

That outer collar of the ZF S6 40 Transmissions is of a different diameter for 90-93 Black Label and 94-95 Blue Label ZF S6 40 Transmissions Throwout Bearings and Clutch Forks

The only hydraulics involved is the hydraulic fluid (DOT 3 or DOT 4) between the Clutch Master Cylinder and Clutch Slave Cylinder. Which Clutch Fluid Reservoir is hidden below the ECM just in front of the dirvers side under the hood.

6. Installation of the Transmission

I ALWAYS use Jerry's Pilot Bearing which has a height of 11/16 inch (.687 inch).

Jerry's Pilot Bearing

You have about 1 inch to work with on the end of the Transmission Input Shaft and I always try to set up the seating depth of the Pilot Bearing to fully install within that last 1 inch of the Transmission Input Shaft.

What I do to insure that.....as I position the transmission using my Transmission jack......it is easy to slide the Transmission Input Shaft Collar through the throwout bearing and the Transmission Input spline through the Clutch Plate (as I recall I have someone depress the Clutch as I install the Transmission).

The Transmission usually slides easily until the tip of the Transmission Input shaft meets up with the Pilot Bearing at which point I have approximately 11/16 inch left for full contact between the Transmission and Bell Housing which dimension is what I am looking for correct engagement of the Transmission Input Shaft with the Pilot Bearing. I then "wiggle" up and down...side to side as I push on Transmission and it always pops in that last (approximately 11/16 inch).

If you do not have approximately 11/16 inch ....Pilot Bearing installation depth may need adjustment.

I do use some good wheel bearing grease on the Pilot Bearing and on the Throwout Bearing, Transmission Shaft Collar before installation of the Transmission.

Last UPDATE of post 35 Dec, 2017

ZR-1 Transmission Install and Lift Tricks
 

ZR-1 Transmission Install and Lift Tricks

NEW 95' ZF S6-40 Transmission (Blue Label)..Harbor Freight 800 lb Capacity Transmisison Jack
https://cimg8.ibsrv.net/gimg/www.cor...5c99dd775e.jpghttps://cimg9.ibsrv.net/gimg/www.cor...0100dc29e1.jpg

1. Transmission Jack
The Transmission Jack works perfectly with the ZR1 on KwikLift 18 inches off the ground (Perfect height). The 800 lb Capacity Transmission Jack has roll and tilt adjustments for a perfect match when locating the transmission on the Bell Housing (Clutch depressed last 2 inches of installation). The transmission (on Transmission Jack) can be rolled under KwiKLift from the front as the shifter will clear the cross members and bell housing/oil pan (slipped along side of oil pan).

2. KwikLift
a. KwikLift (wheels 18 inches off ground).
b. KwikLift Creeper (Perfect with KwikLift).
c. Park Z on KwikLift for ease of inspection under engine.
d. Key in ignition, release park brake, in neutral.....roll out of garage without starting engine.

https://cimg5.ibsrv.net/gimg/www.cor...4bc73c77af.jpg

For those of you who feel like a KLUTZ (Like I did) when trying to get the Z up on an inclined ramp such as KwikLift for repairs when the Z is in non operable condition.....here is a solution.

As you prolly know, the Z can be towed easily using a chain or synthetic tow rope from either the back end (attached underneath to near center of leaf spring) or front end (attached underneath to center of frame cross member). The Z cannot, however, be pushed by another vehicle (The Z can be hand pushed easily but not up inclines) from either end because of the fiberglass on both ends.

I welded a padeye at the center of two 1-1/2 x 1-1/2 x 45 inch long steel box sections welded side by side (1-1/2 x 3 x 45 inch steel beam). I welded two hangers (one on each end of the steel beam). I can just hang the 1-1/2 x 3 x 45 inch steel beam on the end of Kwiklift to pull from the center padeye between each ramp with a wire rope come-a-long attached to the rear or front of any vehicle.

I use a long chain the first two pulls with KwikLift yellow chocks set during resetting of the chain length (the wire rope come-a-long cannot reach from one end of the KwikLift to the other end without starting out with a chain connection).

I call this steel beam KLUTZ (KwikLift Utility Towbar for Zs)
I actually tested the beam (pulled Z up ramp) with just one 1-1/2 x 1-1/2 x 45 inch box section then doubled up in final design.

https://cimg8.ibsrv.net/gimg/www.cor...5b9b35587d.jpghttps://cimg0.ibsrv.net/gimg/www.cor...22753b5a23.jpg
https://cimg1.ibsrv.net/gimg/www.cor...06caf0cd5a.jpghttps://cimg2.ibsrv.net/gimg/www.cor...fa902aebd3.jpg

3. Hydraulic Aluminum Floor Jack (3 ton)
a. Pittsburgh Racing
b. Very low initial height and weighs 55 lbs.
c. High lift rate.

3 ton Pittsburgh Racing Aluminum Floor Jack

https://cimg3.ibsrv.net/gimg/www.cor...3c709ada9e.jpg

See Lifting the ZR-1 for a specific discussion regarding lifting the ZR-1 with a floor jack, jackstands, and ramps.

4. Differences between Black and Blue Label transmisisons
Pete says the 1995 ZF S6-40 transmission has a crash thru detent for reverse which means you have to push a little harder to the right to get it in reverse. The original 1991 has the lock out which is more positive as you have to compress the lock out upward to shift into reverse. The 1991 ZF S6-40 shifer is easier to push to the right than the 1995.

Bill Bourdeau says The ’95 and ’96 ZF transmission (ZF P/N 1052 000 089) has a “crash-thru” shifter with reverse requiring additional sideways force when entering the neutral gate portion of reverse to let the operator know he/she is about to engage reverse gear. The revised internal shift shaft mountain detent pad with raised reverse detent pad causes a brief higher tactile feedback (additional counter-pressure) as the spring loaded detent roller ball must climb up to a slightly higher level just before engaging reverse thus the name crash-thru reverse. Bill's "C" Beam plates are installed (transmission end torqued to 37 ft-lbs and differential end torqued to 59 ft-lbs).

5. Throwout Bearings
I have a 91' ZF S6-40 Transmission (Black Label) Parts List No 1052-000-035 with a collar diameter of 1.373 inches and a 94'-95' ZF S6-40 Transmission (Blue Label) Parts List No 1052-000-087 with a collar diameter of 1.305 inches.

a. Here is a source for the 90'-93' ZR1/LT5 Throwout Bearing Power Torque Systems Throwout Bearing Part #: 23243
b. Here is a source for the 94'-95' ZR1/LT5 Throwout Bearing Power Torque Systems Throwout Bearing Part #: 23244
c. This is exactly what the Throwout Bearing looks like as cited above in both cases as the differences in internal diameter is not noticeable from a picture only.

https://cimg4.ibsrv.net/gimg/www.cor...c83236c1ce.jpg

d. The square end of the Throwout Bearing is prevented from rotating on the transmission collar by the Clutch Fork. The Throwout Bearing slides in and out on the transmission collar when you depress the clutch pedal (Lubricate the transmission collar when installing the transmission so the Throwout Bearing slides freely during operation of the clutch pedal).
e. The other end of the Throwout Bearing which rides against the pressure plate fingers is locked to the pressure plate fingers by a wire clip and always rotates with the flywheel with the clutch engaged or not (the three tabs on the Throwout Bearing are locked between three sets of fingers of the pressure plate).
f. If the Throwout Bearing locks up with the square end forced to rotate, the square end will spread the Clutch Forks completing the failure of the Throwout Bearing as well as the Clutch Fork.
g. As I recall, typically a Throwout Bearing does not rotate at all when the clutch is not depressed unlike the Throwout Bearing of the LT5.

6. Clutch Replacement TIPS (REMOVAL)
1. Drop the exhaust manifolds and release the exhaust system from the two transmission hangers and differential hangers (Or drop exhaust pipes after CATS only). Drag exhaust out of the way.
2. Place jack under oil pan with 2x4 between oil pan and jack plate. Jack up a tad and go to item 3.
3. Remove "C" Frame Bolts and remove "C" Frame. Have in hand ZF Doc "C" Frame Plates for the re-installation of "C" Frame Later.
4. After "C" frame is removed, Lower engine (jack under oil pan) a few inches.
5. Remove universal joint on drive shaft to rear by differential. Mark drive shaft so you get it installed for possible correct balance later. Pull drive shaft from transmission. Beware of transmission fluid leaking all over once drive shaft is removed from transmission.
6. I would drain transmission fluid before I start this job and replace with new Castrol TWS 10W-60 later after reinstallation of transmission. Get yourself a 17 mm Allen Wrench also for transmission plugs. Castrol TWS 10W-60 I just buy Castrol TWS 10W-60 as well as Amsoil 10W-40 (Engine) online. Transmission ZF S6-40 takes 4.4 pints or 2.1 Liters of Castrol TWS 10W-60.
7. On top side remove shifter knob, and shifter boot so you can lower transmission later with shifter attached. The lower you can get the rear of the engine the better but make sure your cam covers do not hit brake booster of fire wall as you lower rear of engine a bit.
8. Remove clutch slave cylinder and leave it hang.
9. Remove transmission bolts (jack under oil pan and with another jack under transmission (the best is transmission jack), use BIG flat head screw driver between transmission and bell housing as it takes some pressure as you jack up and down a bit to free the transmission from the pilot bearing. There are some electrical connections on transmission you remove before pulling the transmission free.
10. Remove bell housing bolts. Pull Bell housing off but watch the throw out bearing as it stays with the pressure plate. The black label and blue label transmissons take different throw out bearings.
11. Remove pressure plate bolts being carefull to loosen bolts equally all around the pressure plate a step at a time. Do not just remove one bolt at a time. Remove pressure plate (it will fall off once all bolts are removed. The clutch plate will also fall off.
12. You might want to now inspect the pressure plate surface and surface of the flywheel.
13. You also want to remove the pilot bearing (there are pilot bearing pullers if it will not come out with flat screw driver wedging it out). I would have a new pilot bearing/bushing on hand.

INSTALLATION
1. Lubricate the new pilot bearing (Lubricate Needle Type Pilot Bearing, Do NOT Lubricate Oil Lite Pilot Bearing).
2. Remember to torque the pressure plate bolts uniformly in steps.
3. Remember to insert clutch plate alignment tool with clutch depressed before trying to install transmission.
4. It also helps if someone presses the clutch as you insert transmission releasing the new clutch plate for better alignment with transmission spline.
5. When you attach bell housing there is a trick to get the throwout bearing mating with the yoke properly.
The Clutch Fork can be slid to the drivers side of the Bell Housing (elongated hole with spring clip) once the transmission is removed. This will disengage the Clutch Fork from the Throwout Bearing for Bell Housing removal and installation.
6. I already mentioned marking the drive shaft and re-installing as it was removed from rear differential yoke.
7. Remember torque on front and rear C4 Beam Plate bolts (59 ft-lbs on rear two bolts and 37 ft-lbs on front two bolts).
8. Use alignment tabs provided by ZFDoc with C4 Beam Plates which align the "C" frame properly with frame just near the shifter assembly.
9. Leave 4 original washers on the rear (Differential) off the bolts. I installed 2 of the 4 original washers on the front (Transmission) bolts as they were originally.
10. The Tranmsmission C4 Beam Plate beveled corner faces toward the front of the transmission.

https://cimg5.ibsrv.net/gimg/www.cor...b996895a20.jpg

A transmission jack is not to expensive and Harbor Freight sells one for $129.

7. Installation of the Transmission

I ALWAYS use Jerry's Pilot Bearing which has a height of 11/16 inch (.687 inch).

Jerry's Pilot Bearing

You have about 1 inch to work with on the end of the Transmission Input Shaft and I always try to set up the seating depth of the Pilot Bearing to fully install within that last 1 inch of the Transmission Input Shaft.

What I do to insure that.....as I position the transmission using my Transmission jack......it is easy to slide the Transmission Input Shaft Collar through the throwout bearing and the Transmission Input spline through the Clutch Plate (as I recall I have someone depress the Clutch as I install the Transmission).

The Transmission usually slides easily until the tip of the Transmission Input shaft meets up with the Pilot Bearing at which point I have approximately 11/16 inch left for full contact between the Transmission and Bell Housing which dimension is what I am looking for correct engagement of the Transmission Input Shaft with the Pilot Bearing. I then "wiggle" up and down...side to side as I push on Transmission and it always pops in that last (approximately 11/16 inch).

If you do not have approximately 11/16 inch ....Pilot Bearing installation depth may need adjustment.

I do use some good wheel bearing grease on the Pilot Bearing and on the Throwout Bearing, Transmission Shaft Collar before installation of the Transmission.

Pilot Bearing

Last UPDATE of post 36 Dec, 2020

Vibration Issues Diagnosis
 

Vibration Issues Diagnosis

1. Is car being driven or is car standing still? (see tccrab diagnoses below)
2. If car is standing still, at what engine rpm does vibration occur with clutch pedal released and transmission in neutral? Belt tensioner, Harmonic Balancer (HB), crank shaft, engine uneven combustion, flywheel, clutch plate, pressure plate check
3. If the car is standing still, depress clutch pedal with transmission in neutral and note what engine rpm vibration occurs? Belt tensioner, HB, crank shaft, engine uneven combustion, flywheel, transmission pilot bearing, transmission input shaft, pressure plate, clutch plate check
4. If the car is standing still with transmission in gear and clutch pedal depressed does vibration exist? Pilot bearing, clutch plate, transmission input shaft check

Assuming no vibration in steps 2-4 above.
3. If car is driven, does vibration occur in all gears at that same rpm (different speeds mph)? transmission input shaft check
4. If car is driven, does vibration occur in all gears at same speeds mph? Drive shaft U joints, drive shaft, short shaft U joints between differential and wheels, wheels, road (try a different road) check
5. If car is driven, does vibration occur with clutch pedal depressed? Let the car maintain speed mph and depress clutch pedal letting engine rpm drop to idle with transmission in gear (this will put maximum relative motion between transmission input shaft and pilot bearing in flywheel). Clutch plate, pilot bearing, transmission input shaft check
6. If car is driven, does vibration occur with clutch pedal not depressed? Let the car maintain speed mph and release clutch pedal (clutch pedal not depressed) letting engine rpm drop to idle with transmission in neutral. Clutch plate, transmission input shaft, pilot bearing check

7. Did you recently (just before vibration issues) change anything? Tires, wheels, drive shafts, clutch plate, pressure plate, flywheel, pilot bearing, "C" Beam bolts, "C" Beam, transmission, tansmission input shaft, transmission input shaft bearings, transmission output shaft bearings, injectors, plugs, belt tensioner, HB, etc. check (The reason I ask is there is always a possibility of an improper installation of new parts or new parts require balance).

What you cannot separate doing steps 1 through 7 above are the following:
A. Clutch plate from transmission input shaft.
B. Drive shaft from differential, short shafts from differential, wheels from short shafts.
C. Flywheel from pressure plate.
D. Flywheel from crankshaft, belt tensioner, HB, uneven combustion.
E. Transmission output shaft from drive shaft.

You can separate the following doing steps 1 through 7 above:
A. Pressure plate from clutch plate.
B. Flywheel from clutch plate.
C. Transmission input shaft from pressure plate.
D. Transmission input shaft from transmission output shaft.
E. Transmission input shaft from drive shaft and drive train beyond drive shaft.
F. Clutch plate from crankshaft, belt tensioner, HB, uneven combustion.

Last UPDATE of post 37 Aug, 2012

Throwout Bearings and Clutch Forks
 

Throwout Bearings and Clutch Forks

1. Throwout Bearings.

I have a 91' ZF S6-40 Transmission (Black Label) Parts List No 1052-000-035 with a collar diameter of 1.373 inches and a 94'-95' ZF S6-40 Transmission (Blue Label) Parts List No 1052-000-087 with a collar diameter of 1.305 inches.

a. Here is a source for the 90'-93' ZR1/LT5 Throwout Bearing Power Torque Systems Throwout Bearing Part #: 23243
b. Here is a source for the 94'-95' ZR1/LT5 Throwout Bearing Power Torque Systems Throwout Bearing Part #: 23244
c. This is exactly what the Throwout Bearing looks like as cited above in both cases as the differences in internal diameter is not noticeable from a picture only.

https://cimg4.ibsrv.net/gimg/www.cor...8d047bb84f.jpg

d. The square end of the Throwout Bearing is prevented from rotating on the transmission collar by the Clutch Fork. The Throwout Bearing slides in and out on the transmission collar when you depress the clutch pedal (Lubricate the transmission collar when installing the transmission so the Throwout Bearing slides freely during operation of the clutch pedal).
e. The other end of the Throwout Bearing which rides against the pressure plate fingers is locked to the pressure plate fingers by a wire clip and always rotates with the flywheel with the clutch engaged or not (the three tabs on the Throwout Bearing are locked between three sets of fingers of the pressure plate).
f. If the Throwout Bearing locks up with the square end forced to rotate, the square end will spread the Clutch Forks completing the failure of the Throwout Bearing as well as the Clutch Fork.
g. As I recall, typically a Throwout Bearing does not rotate at all when the clutch is not depressed unlike the Throwout Bearing of the LT5.

2. Throwout Bearing has two Bearings.
https://cimg1.ibsrv.net/gimg/www.cor...f28bd352c0.jpg
A. When you engage the clutch placing pressure (pulling with the Clutch Fork) on the Throwout bearing the inner bearing is working/spinning.
B. When you release the clutch, the outer bearing is always spinning.
C. The inside collar is prevented from spinning by the Clutch Fork. The Outside collar is always spinning with the Pressure Plate.
D. The Clutch Disk is spinning or not depending on if it is compressed between the Pressure Plate and the Flywheel.

3. Clutch Forks.

a. The Clutch Fork can be slid to the drivers side of the Bell Housing (elongated hole with spring clip) once the transmission is removed. This will disengage the Clutch Fork from the Throwout Bearing for Bell Housing removal and installation.
b. I have a 90 (L98) with ZF S6 40 trans also and I expect that the clutch fork is identical (90 ZR1 (LT5), 91 ZR1 (LT5), 90 Corvette (L98).

c. If a clutch fork fails, I would never try to weld or stiffen a clutch fork (the failure is an anomaly) and the heat treatment of the original is unknown.

d. I have seen clutch forks on Ebay as well as complete bell housings with clutch forks installed.

e. Clutch forks do have three wear points (fingers at the throwout bearing, pivot, slave cylinder plunger) all of which should be greased a tad upon installation.

Last UPDATE of post 38 Dec, 2017