vette_1989

My son and I are building a clone 1987 IROC (a clone of the car he had in high school). The current Z28 car has a rebuilt 305 TPI engine in it, with a T5 manual transmission. He is going to just use the car for Sunday Drives, Power Tours and local car shows. Our current plan is to put a 08-502-8 Comp Cam with Comp's springs, with 1.52 roller rockers to give the engine some "thump". Shorty headers, with true duals to the rear of the car. The car currently has a posi. differential and we plan to upgrade to a 3.73 ring and pinion, to give the car some low end "grunt".
Would like to have some opinions as to what we are doing (good & bad).
Joe

Rolling Thunder

My take on it. Doing a cam swap is good but I think that cam may be a little too hot for your application. Headers are also a big plus but I wouldnt bother with dual exhaust. Its a pain to do and very expensive if you don't do it yourself and if its not done right (and again it is tough) youll have to live with rattles, exhaust leaks, and scraping the exhaust on every bump (which by the way will cause it to rust out prematurely) ect. Not to mention youll notice no benefit in terms of performance over a good stock style exhaust system with a high flow cat and good muffler. Lastly TPI doesnt really like steep gears. TPI primarily builds power in the low end so theres no worries about not having enough grunt with TPI but the 3.73s will make it scream away in a band of RPMs it does not perform so well in. I would tame it down a bit with some low to mid 3.xx gears. All and all I think going with a TPI motor and a 5 speed was a great choice and has the potential to be a blast to cruise around in but be careful about going too radical with parts.

burnout88

I have 3.73's in my car and it is a pefect match. Shaved 6 tenths in the quarter mile with the 3.73's. It's a great gear for TPI. I think a Crane 2032 compucam would be a better cam for what you are going to use the car for.

giszo

You could also have a look on the one step smaller CompCams camshaft with 08-501-8 part number. They say that it is best in 305 and 350 TPI engines.

If you choose one of these cams also make sure that your current cylinder heads can handle the lift the cam produces.

Rod Behring

I have this cam in a TPI 305/5 speed car and it works very well with it. The idle has just a slight lope to it but it still works with the computer.

The car also has 3.42 gears and headers with a good flowing exhaust. My heads are SR Torquers which are just a little better than the stock 081.

Two years ago when I ran it went 13.63 @103 with crappy 2.1 60ft.

More importantly it is fun to drive, with good driveability, and near stock gas mileage.

subroc

iTrader: (2)

Here is the combo that is currently in my iroc (on its way out of the car though)

88 305 TPI
Arizona speed and marine runners
Edelbrock base
ported plenum
LT4 corvette cam (not the hot cam)
Edelbrock headers
Every cheap upgrade in the book
3 inch exhaust the whole way back
3.27 gears
700 r4

It put 216 to the wheels and 261 torque with a retune. I just wanted more lol.

vette_1989

If I go with the Comp Cam 08-501-8 will I need to upgrade the injectors and an adjustable fuel regulator? If so what size injectors and what fuel pressure?

Rod Behring

I have stock 19lb injectors with an adjustable regulator set to 48psi and it runs excellent.

Based on the 103mph trap speed I have 300+ flywheel HP so the injectors have sufficient flow for this application.

subroc

iTrader: (2)

I had stock 19 pounders and it ran great. You will need an afpr. I recommend a TPIS unit.

tenpin842

my thoughts also:
Dual exhaust, don't waste your time and $$, just get the matching Y pipe with the headers, and have it flow into a 3" performance pipe (this pipe is good till 400 - 450 hp), to a nice muffler with dual tips. That is what I have.

Your 1st choice in a cam is to big. I would not go over a .500 lift.
I have the 2023 cam in my car and it's a great match! The Holly stealth ram and a high flow intake would be a nice combo for you. I did the Edelbrock high flow intake and runners with 24# LT1 injectors.
I did need a tune after my swap, so be careful. I had to have it on the dyno adn have it custom tuned.

And don't listen to the ppl who say a 3.73 is to big. You have a T5, maybe go with a 4.11 unless u just want a cruiser then the 3.73 is perfect for that.
Check and see what you have in there now, I had to update to a series 3 carrier so I had to spend more $$ then just on a ring and pinion gears.

best of luck!