Black_80

First time user so forgive me for being wordy! I am the happy owner of a 1980 Black c3. I bought it from the original owner, my brother, 20 years ago. I am very attached to the car and will probably keep it another 20 years. It now uses a quart of oil every 400 miles (leaks and burns). I am ready to do something. If I buy a crate motor or rebuild, I want at least 300 hp. I am not racing but I want to be quicker off the line (at least than my supercharged Grand Prix!). I have talked to a couple of local machine shops and to get above 300 hp would cost about $3300 for the rebuild with assembly, Dart cast iron cylinder heads, and intake. That's with 10.5 to 1 compression. At that price, I think I would rather spend $3400 for a GM HO deluxe crate motor with a new carb and distributor. I would keep the old motor in case 20 years from now that affected resale. I live in New York state so I will need to keep my catalytic convertor for inspection (though they won't test emissions on my year). I plan to use the original manifolds, if possible. I was thinking of the HO deluxe which has 330 hp, cast iron heads, and 9.1 to 1 compression. I probably would never build it above the 330 hp.

Questions (sorry there are so many, answer any you like):
1-Does anyone know if the HO will clear under my hood?
2-will my exhaust manifolds fit?
3-I am told the zz4 has a different intake with better clearance and a friend put one in a 76 vette with headers. Will a zz4 fit my manifolds?
4-If I go zz4, it's about $400 more without the carb. Should I consider my Q-jet modified for electric choke? If not, what carb? My dilema on the zz4 is that, with a new carb I am spending about $800 more for about 25 extra hp and 25 ft lbs of torque.
5-Have most people had good luck with these motors?
6-Finally, any recommendations on where to buy? I have looked at GMPartsDepot.com, Jim Pace, and Summit.

I think I have rulled out a BB for several reasons: engine cost, more cost to make fit car, concern whether the rest of my drive train like the turbo 350 can handle it.

Thanks for any help and sorry for being wordy!

stingr69

I rebuilt the engine in my '80 and added the Dart heads. It did not cost that much because the bores were cherry and that saves the cost of the new pistons and machine work, etc. It runs very well with the L-82 cam and cheap(?) pump gas even with 10.4 C/R.

The Dart heads do not have a heat riser passage so you will have a longer warm-up period. It is not that bad but drivability is low in cold weather for about 15 minutes. The EGR will be disabled as well because of the heads not having the heat riser passage. The EGR valve will hit the valve cover with the Dart heads anyway so you might as well use a block off plate. I got a billet aluminum plate from Ebay for about $15. The temperature sender hole will need to be opened up and tapped to a larger size as they are too small as delivered. Just in case you need to know.

If you do decide to rebuild your current engine I would keep the intake you already have. It is light weight aluminum, costs you nothing, fits everything properly, and works very well with the carb you already have too. JMO.

Either way, you should replace the converter with a newer design higher flow model. The original is sure to be holding you back.

The crate motor is not a bad deal either.

Hope this is useful for you.

-Mark.

mandm1200

Since I have not used a HO or ZZ4 engine, I can not answer with 100% certainty. Either engine should drop in. As to where to buy it, I would not rule out a local GMPP dealership. They may not want to match the prices you see elsewhere, but they'll be able to come close. In fact, when shipping is thrown into the equation the local dealership may be cheaper.

page62

Actually, I only have more questions than answers. First, the '80 has a lower profile hood than the '73-'79 cars. Bear this in mind when people are giving advice about clearance.

Some replacement heads will not work with the stock manifolds. I found that out the hard way after I purchased a pair of Trick Flow aluminum heads. The raised valve cover rail, and its external configuration above the exhaust port, prevented the manifolds from mating properly!

Also, replace the cat with a high-flow unit. It will reduce backpressure significantly while still helping the environment (which ain't all that bad).

The original QJet is a good carb. It might need rejetting...check out Lars tuning paper at www.corvettefaq.com

Finally, do you have a place to store that original engine for the next 20 years? Factor that into your equation...

Black_80

Thanks for the info on the hood, I was about to make a bad assumption. Also, I like the idea of the new hi flow converter.

Black_80

Thanks for the info on your '80 and on the convertor and keeping my intake. When my L48 cam failed I upgraded to the L82 and saw an improvement. I assume you have been happy with the improvement your Dart heads made.

stingr69

Yes, the Dart heads are an improvement. The car now has more than enough power to get me in trouble in a hurry.

If I get the cold start-up drivabillity tuned out I will be thrilled. Otherwise I think there are other aftermarket heads out there that retain the heat riser passage and are worth considering. Edelbrock Performer heads probably have the passage but the Performer RPM do not as far as I know.

-Mark.

humiliategravity

I swapped out my L-48 for a ZZ4 and I absolutely love it. I'm using my original Q-Jet and it works great. I removed the choke completely, which is okay if you live in warm climates. If not, you can always hook up a manual choke into the passenger compartment (the kit is $20).

A ZZ4 will fit your original exhaust manifolds, but you will be stifling it quite a bit. I would guess that will cost you about 20-30 HP. Spend the extra $180 to get a decent pair of headers.

There's a good knowledge base on this forum for ZZ4 swaps, which will help you out when you run into problems. Check out the ZZ4 engine swap FAQ as well:

https://www.corvetteforum.com/techti...=167&TopicID=3

Good luck!

Dave

DaveL82

I have a 1980 corvette that had the L82. I pulled the motor and placed it in the garage corner and went the ZZ4 route. Ran it for a year with the stock auto trans and now doing a 5 speed conversion.

I would go with the ZZ4 agin because of the following:

1)I come complete and the parts work well together (no guess work).
2)You don't have to depend on a machine shop doing good work (risk is minimal)
3)The ZZ4 has great power with roller cam! Roller cam is worth $800 to convert non roller cam motor.

Emissions:

1)The L82 needed an airpump to handle the increased emissions form the L82 cam (more overlap)
2) Made my motor emissions legal since they only check tailpipe and all emission parts are there (no motor serial number match). The car runs clean.
3) The ZZ4 hooks up to stock manifolds and no real reduction is power since stock manifolds are very good. Also note that Brezenzski Racing (ironheads.com) will sell ported vette manifolds used for stock car racing which you could use it needed. If your car does not have an air pump you could run 2.5 inch exhaust manifolds instead of 2.0 inch stock. For air injection only the 2.0 inch exhaust manifolds had injection ports.
4) The roller cam actually has less emissions and a lot more power than the L82. This is because of high lift and reduced overlap possible with roller cams. The L82 cam is old tech and should not be used for it's minimal gains. More up to date flat tappet cams can be used however they will never match a roller without increasing emissions a lot, running rough as overlap increases and mileage will suffer. Note that down the road if you do change to a higher performance roller cam such as the hot cam kit the rollers can be reused unlike a flat tappet cam.
5) I run all the stock emissions stuff on the car so it looks stock. You may want to spray the aluminum heads black to get through a visual inspection.
6) I believe Brian Seery also has one in his vette and it passes emissions tests if I recall correctly.
7) note stock aircleaner only just fits so tolerances in motor mounts may require 1/4 inch be milled of top of manifold that comes with ZZ4.
8) ZZ4 intake will take all emissions stuff anfd flows well. EGR will no longer work becuase of missing head cross over.
9) Stock carb runs great and also have older spreadbore double pumper than is a rochester replacement that I tune for max power and is a 20 minute swap since all things are in the same place including the fuel inlet in front to bowl like the rochester.
10) change to short water pump is required for ZZ4 swap as well as using smaller diameter harmonic balancer (reuse old or buy new). You will have to machine a couple of the timing cover bolts to fit the water pump or just swap bolts to ones with lower head on them.
11) If an automatic swap the converter bolted right up and motor comes with flexplate (automatic flywheel). Starter must work with smaller diameter 153 tooth flywheel.
12) The ZZ4 motor is so good a lot of stock car santioning bodies are now using them for spec class motors.

If you go with new roller cam technology you win all around with more power, low emissions and better gas mileage so I believe this is the main reason to go with a ZZ4 motor. Try to build another roller cam motor for that.

Dave

Alwyn678

I would definently rebuild the stock motor and put in a nice cam and some performance heads as well and some headers and flowmasters will make her breathe a bit better

Black_80

Dave, that is a lot of great advice. I think you have sold me on the ZZ4. I didn't know all of the advantages of a roller cam for power, emissions, and economy. Thanks!

Black_80

Dave, thanks for the advice and link. That was a lot of specific help!