ok, i'm going for a buildup on my 305 TPI...what aftermarket heads are the best for the money and what size combustion chamber should i go for.....i'm not sure what size mine are stock, i've heard 64cc and i've heard 58, which one, and what would going w/ a larger combustion chamber do to my performance? pros/cons?? help!!

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88 Trans Am, 5.0L TPI, flowmaster cat back, high flow cat, WS-6 performance suspension, black w/ t-tops, automatic transmission....soon to be armed w/ a 5.7 TPI

 

Your stock 305 heads have 58 cc combustion chambers. The Vette heads have the same size and will bolt up nicely, although they don't have the EGR ports in them. With a good cam (like 210/220), these heads, headers, and the usual mods, you could be running in the low 14's to high 13's depending on traction. A larger chamber would make a little less power since it would drop your compression ratio (stock is 9.3:1).

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Greg Westphal
'87 IROC 355TPI/A4

 

World makes some pretty nice (and cheap) iron heads for the 305. They are a stock replacement head so you shouldnt need any machine work that you may need on the 58cc vette heads. But then the vette heads are aluminum and might be worth the work. The worlds are supposed to perform pretty well, but I do not have them so may want to check with someone who has done the install.
peace

[This message has been edited by 85transamtpi (edited October 18, 2001).]

 

The Vette heads won't need any machine work, and they'll easily outflow the World Products 305 heads. You won't be able to run your EGR, but that shouldn't keep you from passing emissions (I passed w/out the EGR and the AIR system).

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Greg Westphal
'87 IROC 355TPI/A4

 

i guess i could pick up the Vette heads from Next Generation...i think they're in there.....EGR ports....what do they look like...i'm new to this fuel injection stuff..my old Charger didn't have anything for emissions.....is that the tubes that come out of the manifolds? i don't mean to sound stupid but i'm still learning...this is a whole new world to me

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88 Trans Am, 5.0L TPI, flowmaster cat back, high flow cat, WS-6 performance suspension, black w/ t-tops, automatic transmission....soon to be armed w/ a 5.7 TPI

 

The EGR ports are also known as exhaust heat crossovers or something like that. They are in the center of the intake side of each head, I think a small circular hole. The tubes coming out of the exhaust manifolds are for the AIR (Air Injection Reaction?) system that pumps air into the manifolds (while the computer is in open loop) or into the catalytic converter (in closed loop).

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Greg Westphal
'87 IROC 355TPI/A4

 

I was told that the L98 vette heads will need minor valve schroding to fit the bore of a 305. This sounds like a logical conclusion. let me know if I was miss informed. JMO

 

with the EGR, what runs to what in the event that i switch heads....i know to make this run i need a good set of heads...don't know if porting my stock heads would be good enough and i don't want to make a mistake

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88 Trans Am, 5.0L TPI, flowmaster cat back, high flow cat, WS-6 performance suspension, black w/ t-tops, automatic transmission....soon to be armed w/ a 5.7 TPI

 

serious disruptions on this board all the sudden, huh?

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88 Trans Am, 5.0L TPI, flowmaster cat back, high flow cat, WS-6 performance suspension, black w/ t-tops, automatic transmission....soon to be armed w/ a 5.7 TPI

 

I doubt you need to do any work on the Vette heads, although they could always use a nice clean-up port job just like any other factory heads.

Concerning the EGR, the exhaust crossover passage in the pass. side head feeds the EGR. The way the Corvettes handled this was to run a line from the exhaust manifold up to the EGR they had mounted near the rear of the intake manifold. I'd just block off the EGR opening on the top of the manifold and not worry about it if you don't have to pass a visual inspection for emissions, but that's just MHO. If you really need or want EGR, then getting the World Products 305 Torquer heads and having the ported out would help your engine make some decent power. Porting the stock heads would also work, but just not as well...

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Greg Westphal
'87 IROC 355TPI/A4

 

wouldn't need to machine the engine to make them work or will they fit right on...also, will the larger combustion chambers really screw up my engine or not..b/c i know low compression is good for power adders which eventually i'll be investing in....by the way, i appreciate the help guys.

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88 Trans Am, 5.0L TPI, flowmaster cat back, high flow cat, WS-6 performance suspension, black w/ t-tops, automatic transmission....soon to be armed w/ a 5.7 TPI

 

corvette L98 heads or Edelbrock heads......not sure which way to go.....know i need something strong to handle the eventual power adder i'm gonna throw on

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88 Trans Am, 5.0L TPI, flowmaster cat back, high flow cat, WS-6 performance suspension, black w/ t-tops, automatic transmission....soon to be armed w/ a 5.7 TPI