I have an '87 Z28 Camaro it had a 305 TPI HO engine in it. I put a 305 TBI engine from a '91 RS in it. I took the TBI intake off, and put the TPI intake on the '91 305 block, and didn't change the cylinder heads or cam. When I was done it ran good but the distributer wasn't tight so after a day it started backfiring, it blew my muffler apart, started missing, ran at 500 rpms, and when I turn my heat on it loses power and sputters out. I tightened the distributer and timed it, put in new plugs and wires, cap and rotor, fuel injecters, fuel filter, changed oil and filter, new cayt. and muffler, MAF sensor, fixed check engine light problems, and checked fuel pressure (good). I drove it for a day and it started running the same backfiring, missing, idleing at 500 RPMs and when I turn the heat on it loses power and sputters out. Could it be that the '91 305 TBI block is different, like the cylinder heads and cam? Is it supposed to idle at 500 RPMs? Can someone help me, please?

 

recheck your timing,make sure it didnt move 1 tooth when dizzy was loose.isee you also put new wires on doublecheck firing order.the losing power when turning on heat makes no sense to me,dont know why this would happen.keep us posted,later jimmy