Got a question been looking all week for answers and still nothing found yet. I got a 94 Z28 i just put a 355 LT1 in my car with cam, cam specs duration .050 intake .230 exhaust .236 valve lift .510/.520 with 1.6 roller rockers. I started the motor for the first time monday and it ran good just had to adjust the valves and tweak on some odd and end things but over all started good no horrible issues. The only running issue is it's backfiring through the exhaust below 1500 rpm, it won't idle, and it's running extremely rich. A couple of times this week i was able to get it to idle with little to no backfire. Now my question is with it running extremely rich like it is will it cause it to back fire like this and is the answer a tune to stop it from running rich and the backfire?

Thanks for the advice and help
Chis

 

Have you reprogrammed the PCM for the new cam, or are you still running the stock tune? If you haven't had it tuned yet stop running it until you get a new tune loaded.

 

i have not reprogrammed it yet still running stock tune. i have stopped running it til i can tune it

 

That is your first problem. You've changed everything about the motor but the PCM still sees it as stock. You need that baby reprogrammed to even have a prayer of it running right!

 

ok thanks i appreciate the insight thats what i was started to think but i was starting to wonder bout some to