i'm close to buying an 87 IROC with a ZZ4 engine. it currently has 3.27 gears in the back. my friend says that 4.10s would make the car scream, but i think they might be a little too agressive. i think the 3.73s would be good. which ones would be better?

 

bump

 

It depends alot on what induction you use....

If you use TPI on it, I wouldn't go past 3.42; TPI works best in a somewhat lower RPM range, so stick with its strength. If you carb it, it will be able to produce meaningful power at a much higher RPM. 3.73 would be best for street use, or if it's a mostly strip car, 4.10s would be OK if it's a stick car. If it's a 700R4 car, 3.73 is probably as far as you'd want to go.

 

it's automatic. i was thinking of going with the Holley Stealth Ram or Super Ram, but i don't know much about them.

 

i have a ZZ3, pretty much same motor, and im running 3.73s....good street gear, doesnt rev to to high,,,also have a 700r4,the OD helps a lot... which im gonna scrap soon for a th350...

 

i have an 85 iroc with a stock built 350 zz4 cam, camelhumps (the 1.94, 1.50s) and a factory TPI setup, aFPR, and i have a 3:23 open rearend, I have factory sized tires 245/50/16. The car breaks the tires as soon as you put it in drive!! if you nail it from a dead stop, it burns all the way thru 1st,hits second and just about becomes gutless! I want to go with 3:73 but i think that might be too much gear, i just feel the gear i have is not enough will a 342 posi be able to get traction? and still hold up???

 

I was running 3.73's in my 84 TA with a ZZ3 and 5-speed.