i recently put a new 350 in my IROC-Z and i can tell a quite a bit of difference in the performance, its not as fast as it wuz before i replaced the motor, the motor wuz a pretty cheap stock replacment from a local parts store, i heard from many people this is normal, i have only put 460 miles on my car, it seems like the power is coming back slowly but i cant really tell yet, will i regain all my power?? and how many miles will it take to get back to normal, Thanks for your help!

 

I hope you changed the camshaft along with the heads on that new engine. The ones that come right from the part store stint. Did you move from a 305 TPI to a 350 TPI? If so did you change your injectors, knock sensor? I'm thinking you got a "basic" 350 then put your TPI stuff on it.

 

Yeah he's right, a parts store 350 is your basic generic parts 350 with low compression, crappy cam & really crappy heads! To wake your motor up change the cam to a low compression high torque type. The cam will trick the motor into thinking it has higher compression than it really has. If u have the money buy the Vortec heads & tpi intake that fit those heads & be happy!
njdaewoo

 

I have NO money i have only put 460 miles on the motor since ive gotten it back, so im gonna give it till about 1000 or 1500 miles and if i dont think it runs as good as before im gonna try to sell it for about 3000$ and start over and bye a new iroc, and my car wuz a 350 to start with so that shouldent be a problem