Recently Rebuilt LT1 attached to 95 Z28 with 6-speed Tranny. Flowmaster exhaust. Engine starts sputtering at 3800RPM Under hard acceleration and gets worse as the engine heats up. After engine is up to running temperature, the engine pops out the exhaust regularly. I have set the valvelash four different ways while running and not running. Currently I have the O2 Sensors disconnected, and that has not effect on the performance at all. After Disconnecting the O2 sensors, I did not get a Service Engine Light unit after I drove the car, let it set, then it came on. The Engine does the same thing without even having O2 sensors hooked up. I put a new Opti-spark in during the rebuild too.Running Ac Spark pugs set to .050"gap, New Wires too.

Original Failure due to Lack of Oil and Spun "bearing. Had to get another Block and Crank. I got a GM warranty sale part from a dealer in Louisiana. Got the LT1 shortblock from him, then rebuild from that. According to Lousiana Man, it had 600 miles on it.

NOW: Heads redone from original LT1, ported , shaved, Lapped, and powder coated. New Springs and Valves. Block Precision Bored to match each piston At .028 to .032" over depending on size of piston in the Performance Rebuild kit.

 

sounds similar to the problems im having, it could be the coil or the icm(ignition control module), does it run fine when the car is not warmed up? if so that is the exact problem that im having

 

I'm FAR from an expert, but it sounds like this motor should run really nice!.... If the mechanicals are in order, that just leaves ignition and fuel. Are you using the original stock injectors? How clean are they? Can you check fuel pressure? Are you getting NO CODES at all?

Hopefully one of the LT1 geniuses here will pipe up with your solution. Good luck man.

-Michael

 

I am happy to say CamaroZ28.com opened my eyes to some new ideas. I Went out yesterday and pulled the Fuel Injector connector off my #6 cyclinder, as it was my suspected problem area. I do have a bent exhaust valve on #6 cylinder. Problem Found/ It makes me happy I found it, although, I am sad to have to pull that head off and pay to fix it/ Ha Ha

Thanks to everyone,

Greg Stokes
Z28tech