Well I've been snooping around here for a little while. I recently picked up a 90 Iroc in a bit of a project state. Most of you guys seem like you've been into engine combos quite a bit. I thought maybe you guys could could give me your 2 cents on some of these parts the previous owner put together. How well they go together and maybe some power estimates?

A little background: the TBI 305 is out of a 90 RS that he rebuilt the long block to stock specs. and installed a Crane powermax 2020 roller cam. Advertised duration of 256/266; @ .050 194/204 and .407/.429. He ran about 4-5000 miles on it in the RS until he picked up a 90 Iroc. (He said the engine ran great in the RS) Then he installed the long block in the Iroc along with the TPI set up. He had the prom flashed for these specs. He drove about 50 miles on this set up until the auto trans went out so he swapped the T-5 from the RS into the Iroc. At the same time he installed 1.6 roller rockers and advanced the cam 3deg. and has not re-flashed the prom. Would 1.6 rockers and 3deg. be enough to justify re-flashing the prom?

It runs really good(except for the 2.73 gears! this is very high on the list of future mods) It does seem to be running rich. I smells rich at the tailpipe.

Anyway, sorry to make this so long. I'll just tell you I have NO codes or check engine light(computer seems to be happy) It does have headers, BBK 58mm TB, AFPR(I haven't checked the pressure yet), stock 19lb injectors. I have a new cat to install but I want to make sure the motor is dialed in before I ruin a new cat. ( I do live in CA, smog requirments)

Thanks for all your help guys!

 

The main problem above all others is those swirl-port heads.

 

So do you think the rest of the parts are a good set up? What heads do you think would go best with these parts?

Thanks Atilla

 

That cam is going to be the next bottleneck once you upgrade the heads, even the stock LB9 cam is more agressive. You have several choices, but I'd do 3.42:1 gears, then heads, before thinking about a cam. The thing is having the better heads set up for up to .530 lift before installing them, so you can have more choices of camshaft.

 

I'm glad you think I should do gears next. I want to change those so bad! I have to feather the clutch so much when I take off from a stop, it's ridiculous. This is in no way a daily driver so I'm even thinking of going to 3.73's. The T-5 is from a TBI 305 RS so I believe it has the taller overall gearing with the .63 OD from what I can figure out. So after spending some time on a RPM calculator I thought I might go with 3.73's. Do you think it's still too low? Thanks

 

I think 3.73:1 gears will be an excellent choice for where this project seems to be headed.