I have some 89 aluminum vette heads to put on my 87 305 tpi 5 speed iroc. I have done a lot of research on porting and polishing heads. Still unclear on best route to take.

I am not looking to race the car, just want the best performance without losing too much fuel economy. I just got beat by a suped up prelude the other day. WILL NOT HAPPEN AGAIN!!!!

I am rebuilding the engine, tranny, and rear end.

The car is stock right now. I have to put on:
edelbrock headers with y-pipe,
hi-flow cat
edelbrock cat back.
AS&M runners
a set of corvette injectors if needed
May put 1.6 roller rockers on
52mm TB
Will have plenum ported and everything gasket matched

Will i need a aftermarket base with all this stuff or just port stock?

Any other mod and suggestions will be greatly appricated.

 

If you are going to rebuild the engine, build a 350 instead of the 305...... even with the core exchange you will break even due to 350 parts being cheaper. Besides, the L-98 heads are designed for a 4" bore instead of the 3.735" bore of your 305. As far as that goes, the L-98 doesn't have good flow numbers compared to anything aftermarket. Try a set of AR-190cfm heads and a ZZ9 cam from TPIS or a ZZ4 GM cam. your power range will be (realistically) from around 3000 to 5500RPM.

Talking to guys with similar engine setups, mine seems to pull harder to a higher RPM with Hedman headers than they do with Edelbrock headers.

Definitely go with roller rockers, but no 1.6's if you buy one of the suggested cams.

Go with 3.73 or 4.11 gears in the rear end. You have overdrive that will help on the mileage. You could still pull 24+ highway with the suggested combo. I have a heavy car (3600#, with 250# driver) and have gotten 24.5 mpg, of course that was when I had lightweight pistons in the car…. Haven't had a long run of freeway driving to check it since I rebuilt the engine and added heavier pistons….

With the recommended cam and headers, I would definitely suggest an aftermarket manifold and runners. I would not recommend Edelbrock runners as they are such a royal pain in the rear to install and keep leak free. The Edelbrock manifold has soft metal in it as well. About half of my bolt holes are helicoiled now. Of course I've had the parts for 11 years and have had the TPI unit apart a dozen times…..

Don't know what difference the 52MM will do for your 87, but it works wonders for an 85!!!! With an 85 computer there is a bog when you hit 3rd gear, the 52MM TB eliminates that bog. With my 89 computer installed, there is no bog when shifting to 3rd gear…. TPIS does recommend a 52MM TB when using one of my suggested cams….

Bottom line: Do what you can afford to do! Just plan your final goal and the best way to reach it!!!!

 

I would go with the 350, but I want to keep the car as close to stock as possible. Which means keeping the original block. That is why I am interested in doing just a few mods to give my 16 year old car a little more punch to hang with these 4 bangers and 200+ HP V6's.

I'm not really looking to drive my car that hard that is why I was wondering if just putting some 1.6 rockers would help instead of putting in a new cam

Would 3.42 gears be enough? Not sure what it currently has in it. The RPO codes are in the console and it is in the gararge somewhere.

Do lightweight pistons really help? What would anyone suggest for a 305?

Still need a clear answer on what and how to port my heads.

 

Hey Capt C, You say that you had leak prob's with the runners-where? I have only 140mi on my new eng cause of a massive air leak, I think it's the o-rings around the injectors but I'm still wondering it there's more. I used starter fluid to thy and find it.
It's somewhere around the pass side tubes. I just love the runner bolt hole that goes into the water crossover.

 

The leaks were usually around the bottom of the plenum or at the base manifold. You have to tighten the lower set of bolts into the plenum first, and then the lower bolts, finally the top bolts. This is for Edelbrock runners only!!!!!

The bad thing about TPI is that the old carb tricks for finding vacuum leaks don't really work because the computer adjusts so quickly. You need to get a stethoscope and listen for leaks…..

You need to make sure the cold start injector is seated all the way as well (if applicable to your year car)....

PS: Old Squid here myself!!!!! Go Navy!!!!