Hey i have a 1994 z28 with a T56 6 speed, i had the heads ported cleaned up the bottom end had a custom grind cam installed with new springs and 1.5s, moroso cold air intake 4.10s(which i have no installed yet but completely needed) full length headers, 3' flowmaster dumps (which scrape on everything!) i think i am missing a few things but i have the stock throttle body on it and i have to turn up the idle to about 1000rpms because other wise it will stall, my mechanic told me it was because of 'idle surge' and told me to drill 2 1/16th holes in each of the butterflies because that would let more air in at idle, but i want to know if a 52 or 58mm TB would work and if so which should i choose?

 

You need to get the PCM tuned to account for all your mods. Messing with the mechanical settings or drilling holes on your throttle valve will just confuse your PCM more. The idle speed is controlled by the IAC valve which is controlled by the PCM. The 52mm TB will work fine but won't fix your problem, you will still need a PCM tune. Do not mess with the TB stop screws, they are not there for adjusting idle speed.

 

thanks man, any idea on who can tune an lt1 computer because i cannot find someone

John

 

Jet Chips does custom chips for older chevy's, you might want to try them. I've heard both good and bad things (but that's true with anything on this forum, really) Not sure how far up they go on custom chips, but it may be the easiest way to do it, if they make one for your car.

 

The PCM in your car does not take chips. PCM for Less will tune your computer on an exchange basis. www.pcmforless.com

 

you some times still have to reset the idle manualy. In camaro performer they said to adjust the butterfly to where the car idles the move the throttle position sensor to where it reads the rite voltage some fileing or drilling of the holes in theTPS is required to adjust it. I can't find that issue but they give the rite code.