Hey guys, I used to have a 92 rs with the 305 tbi and it was slow, with 2:73 gears it would still burnout (open diff). Now I have a 89 IROC with the 305 tpi, same gear ratio and posi, I can't spin the tires on a dry road to save my life lol. These are the only 2 305s I've had so I'm just wondering if they're just supposed to be this bad, I heard the tpi had a lot more power than the tbi but it feels the same to me. My 99 silverado 5.3 feels way faster. I put a cammed 350 in the rs and that ran low 14s with the 2:73 and open diff. I'm not expecting that kind of power but I though these cars ran 15s?

 

You might have had bad tires on the old 305

 

They're the same tires! Lol the 350 would roast them and now I can't do a burnout

 

Part of the issue is that you now have a posi rear in the IROC. The engine is trying to spin both wheels instead of just the one.

 

All the stockish TPI 305 cars ive driven or rode in have NO PROBLEM spinning tires. With posi.
There must be something wrong. TPIs are torqey.

 

There is something wrong with it then. A TPI 305, hell even an LO3 should lite the tires up no problem.

 

Exact ill what I thought! My lo3 used to light up one tire lol, this motor is supposed to have way more power. My ECM is throwing no codes as well, so I don't know what's wrong, nothing sounds or looks wrong.

 

Your cat-converter may be stopped up i had this issue once.

 

Yup I had a bolt on lt1 with 4.56s that I picked up for a grand because the previous owner thought the motor was whooped lol

 

I don't have a cat lol

 

This right here.
I'd bet money there is nothing wrong with it. A 305 TPI with a peanut cam, airplane gears like 2.73 or 2.77, and a posi rear will not spin a decent pair of tires without using the brake. My car probably runs better than 3 quarters of the cars on this site, and it won't bark the tires from a dead stop.

It doesn't have "way more power". Your L03 made around 170hp, the LB9 makes around 200hp. Do the math.

 

30 horsepower is a noticeable difference, anyway the problem is fixed and now I can light up both tires no problem, with 2:73 gears.

 

What was your issue?

 

Lol, don't laugh! Please! My #7 and #4 plug wires were mixed up, and my ECM was no good, it wouldn't advance the timing at all. New one is great!

 

You thought the car was running just fine with two cylinders misfiring?

Either way, you probably have better gears than 2.73 in the IROC.

 

It was running smooth just no power, no shaking or anything either. My rpo codes say 2:73 gears. Rpms at 65 mph is like 1600