TedH

You can get IE's with 72cc chambers. If you are starting with 9:1 compression, that bumps it up (assuming the chambers are 72cc) to approx 9.5:1. I went with the 72cc chambers.

One caution, IEs do not have heat-crossovers so 'cold' performance, until warmed up, is not optimal. Must admit though, with these heads, I get the full performance potential of the Performer intake, new HEI, cam, pistons and headers. They flow respectable numbers through my cams lift profile.

KJL

Are you sure it will fit under a "72" wiper door hood? Where are you measuring the 1.5" from? If it is from the top of the bolt to the hood, this would tell me I could use almost any popular intake including the RPM air gap with a drop base air cleaner and I am quite sure I can not. With a drop base and stock intake I have about 3/8" gap between the bolt and the hood. I know there are diff drop base cleaners out there. I wish they would indicate the amount of "drop" from the cleaner mounting flange in the ads.

KJL

You will not see much gain in changing the intake and carb. I do like the Performer carbs however. They are easier to dial in than the old Q-Jet and are affordable. If I didn't enjoy wrenching, I would have pulled my q-jet by now. It has been one PITA. Anyway, The secret really is in matching all the components. Dollar for dollar the first thing you should do is install headers, I used Dynomax ceramic coated with a 2 1/2" exhaust through a pair of Flow Masters. Make sure you have a good coil, low resistance wires and plugs. Time your engine to 36 degrees at about 2500 rpm. Lars has a paper on how to do this, he also sells the spring kit and new vacuum advance can. You get these from Summit as well. The Performer (2101) intake will fit under the "72" though I am not sure if it requires a drop base air cleaner to fit. It has an average centerline dim of 4.05 inches. The EPS (2701) is 4.27 inches. The Vortec is 4.575 inches. Most street carb's i.e. Performer, Q-Jet, Holly, and Demon are 3.25" from base to air cleaner flange. The Performer carb will take square bore or spread bore carbs. I believe the EPS is square bore only.
The stock L48 heads have 76CC combustion chambers with 1.94/1.5 inch valves. Your CR is 8.5:1. Going with 64 CC chambers will put you in the 9.5:1 range. Spend the 40 bucks and get the Desk top Dyno 2000 program and learn how to input values for the cams and heads. This will be a great guide as to what the best combo for you will be. Be aware of the "bigger is better" mentality you will run into. When it comes to heads and performance in the drivable rpm range, velocity is as important as volume, maybe more so....

KJL

You get to keep your valve covers too!! Vortecs are center bolt.

KJL

rpounds,
I just installed a Transgo shift reprograming kit in my Turbo 400 along with an adjustable vacuum modulator. Wow, what a diff. Good quick shifts (not harsh) it really gets the power to the road. I have adjusted it to not shift as quickly thus getting higher in the RPM/TORQUE range at the shift points during normal driving conditions. Before I almost had to be at WOT to achieve same. With your combo I bet it would kick butt!! One afternoon, 100 bucks including kit, oil, filter and gasket from NAPA and a 12 pack of beer. Dollar for dollar and seat of the pants feel, one of the best mods I have done so far. :yesnod:

Smokehouse69

KJL, Vortec Performer and Performer RMP have dual pattern flanges that will work with a square bore or a spreadbore carb. The exhaust ports are not a problem either, original ramshorn manifolds will bolt right up to Vortec heads, Dynomax headers work too.
Springs on Vortecs are weak, and need to be replaced if you go with anything bigger than a Comp XE256 (I used stock springs with an XE262 and had no problems) The self guiding rockers aren't a big deal either, for less than $100.00 most machine shops can pull the pressed in studs and install threaded studs and guide plates. Then you can use any type of rockers you want.
Comp sells a couple of tools that you can purchase for less than a $100 that will allow you to widen the springs seats and cut down the valve guide higth with a 3/8" inch drill at home. If this worrys you then have a machine shop do it, it shouldn't cost much more than $100 either way.
Z-28 springs and retainers are cheap and perform good enough with most high lift cams.

KJL

I just checked out the Edelbrock web site and it shows the Performer RPM as a square bore only. Thanks for the info, I can't use the Vortec heads regardless because the intake will not fit under my "72" hood.

l2vette

Thanks for the all the great info!!!!
:cheers:

KJL

Its nice to give back from which I take so often. :)

glen242

Vetticus Supersonicus:

I have a '76 L-48 like you. Check my signature for the mods I have done. Well satisfied with the performance. DD shows 370 HP @ 5500 rpm and 417 ft/lbs of torque @ 3500 rpm. I did the work in 2 stages, leaving the heads and intake for last. Intake went from a Performer to a Performer RPM (for spreadbore) the second time around.