I have a 1962 Chevy Nova with a TPI on a 383 with Eagle Crank and Rods, Speed Pro flat top pistons Comp Cams XE268 HR Dart 180 Aluminum Heads 1.6Roller Rockers, Accel 24lbs injectors, 58mm Holley Throttle Body I had a chip burned by Harris Performance. I've had the chip for at least 1 year. I did some work on the engine bay and pulled the engine. I pulled the engine down to rebalance since I changed from Automatic to Stick and changing the flywheel I wanted to balance the entire assy. I put the Comp Cams XE268 HR with new roller lifters pushrods, and installed new matching springs in the heads. The engine runs real good for about 10 minutes and then it starts acting like its missing or laying down. I went to a cruise night and about half way there it started laying down but when I got there and shut if off and let it cool down when we left it was running good but about half way home it started acting like it was laying down. I'm only running around 190 degrees. Any ideas would be great.

Mitch

 

I'd check out the ignition system. How old are the plug wires? It could be the module going bad too. It heats up and stops working right, then cools down and works fine again. Also, can you check fuel pressure when this happens? It could help you rule out the fuel side of the engine. Check your TPS voltage too (you want near zero closed and close to 5v when at WOT). This doesn't sound like a mechanical problem. It's definately an electronic issue. If the engine ran right before I would not suspect the chip or ECM. Is the car mass air? If you I would test the MAF to amke sure it is working right. The MAF is the source of a lot of problems, which I think is the real reason GM went back to speed density EFI. Ford figured it out in '86, but GM needed until '93 to get it right.