CamaroRS21

I have a 92 RS that use to have a 305TBI in it, it wouldnt enough power, so i bought a 91z28 parts car for the 350tpi in it. Turns out the z28 wasnt in bad shape at all, i drove it for months and loved the power it had. I finally got the motor swapped though, took the 305tbi out, put the 350tpi in my rs. Swapped computers and wiring harness also. First start, it cranked for a few mins before it started, finally got to drive it, and it ran like crap. So i figured the 305 fuel pump wasnt putting out enough for the 350. So put a new fuel pump in. didnt fix it. So i put new plugs, plug wires, cap, rotor, button, vaccumm lines, and a few other little things on it including gaskets from intake up. It helped but not much. The same mechanic that put my gaskets on says there was so much built up carbon in the motor he is surpised it even runs. If that was the case then why did it run so good in the z28? My questions are... What could have went wrong during the motor swap? Should i have changed rear ends? should i have changed transmissions? What else should i do? Way too much money into this car to give up. I want the power back that it had when it was in the Z.

five7kid

iTrader: (14)

Did you swap the exhaust?

CamaroRS21

No? why would I have to do that? I cut it off halfway back

five7kid

iTrader: (14)

'91 TPI is a speed density system and is sensitive to changes like exhaust. Not saying that's your problem, but the TBI exhaust is pretty restrictive compared to the TPI exhaust.

CamaroRS21

I have the exhaust cut off right in the middle. No cat or nothing. Just straight pipe. I understand what your saying but i dont think it would make it run as bad as it is. After driving for about 2 hours it gets really horrible. It gets to were it dont wanna run at all. But on a cold start, it runs pretty decent. Just a small miss. When the motor was in the Z28, it ran so good, i mean it ran amazing.