Hey I have recently aquired an 87 IROC-Z w/ the L98. I have done some research on here about modding the TPI, I have come to the conclusion that it gets very expensive to mod the TPI. Is it's possible to run solid 12's on stock heads, with a cam change and a carb conversion? If so what setup is recommend for carb, manifold, and cam? Also could anybody point me in the direction to instructions that show how to swap over (not sure what all needs to be changed) Thanks!

 

http://5finger.8m.com/tpi2carb/tpi2carb.html

Doing the same swap. I'm using a 600 cfm carb temporary, a ZZ4 cam, Edelbrock performer manifold( til I get an air gap).

Basically you need a carb, intake manifold, electric or mechanical fuel pump, new distributer. And I'm sure theres more.

Good luck!

 

Of course it's possible to run 12s with that. People have been doing that with that motor since 1969. Once you remove the TPI, it's just a 350, like about any other 350; and once you swap the cam, it's all wide open. It even has halfway decent heads on it, from the factory.

ANY cam/intake/carb combo that will run 12s on any other 350 with similar heads and compression, will run the same on that one.

A ZZ4 cam, Performer intake, and 600 CFM carb won't cut it. That combo is strikingly similar to a ZZ4 top end, which as everybody knows, a ZZ4 runs mid 13s in one of these cars, with the right size perfromance carb as opposed to a 600 CFM Carter; around 13.4 with a 750 Holley, and after the drive train has been set up better (like, lose the 2.73 gears). Figure 13.6 with the too-small Carter; about 14 flat with the stock L98 gears.

You should be able to get to 12s with a XR276HR cam, a Perf RPM, and a Holley 750; and of course, headers & exhaust, and gears, and a converter, and some suspension work to get it to hook up.

 

Im working on it.

I am running the L98 with ported AFR 190 heads, a comp xr282hr, rpm airgap, and either a holley 750 vs or a 750 vs demon. Hedman Lt's with dual exhaust, 3.73 gears, th350 trans and a 2700-3000 stall with 26" tall tires.

I hope to be in the 12's.

 

I know a 600 won't cut it, ut I was jsut expaining to him what I'm running temporarly.

 

Great info thanks for the help! But will the stock valve springs handle the extra lift? If not what is the stock springs limit on lift?

 

There's ALOT more to valve springs, than "handle the lift".

Your stock springs won't cut it. They barely control the valves with the weenie little cam in it now, or maybe they don't even do that. They CERTAINLY won't be enough for any kind of a performance cam, that will get you into 12 second territory.

Your heads would benefit from some porting, and some better quality valves. When you do all that, set them up with the right springs for whatever cam you decide on. The stock cam won't mind.

My comment about the 600 was sort of just thrown out there, since it had been brought up.... sounds like Could will have himself a nice peppy ride, it should run just fine, but it won't be a 12 sec car; and the carb will be one of the first limits he encounters to his setup's performance.

 

I'd suggest a 750 Holley 4150 or 4160 carb, Edelbrock RPM or RPM Air Gap, and an XR276HR cam from Comp (its a roller cam, so it should work with your existing lifters)