84 camaro. 400 small block. Sportsman 2 heads. Victor Jr. Intake. Summit 1108 cam. HEI dizzy. Long Tubes. Holley Black Electric Fuel Pump. Holley 750 DP. 4.5 power valve,about 9psi of vacuum at idle. T5 Tranny. Fuel pressure at 7psi. Need to know anything else just let me know.

So I parked the car with no problems. Came 2 days later to start the car, and it started backfiring like crazy. It cleared out for the most part, but when driving it you can almost feel a small miss but under heavy acceleration it backfires some and what i think may be it missing sometimes worse than others and just doesnt seem to have the power it did. Things iv tried are: 2 different coils,shut the lights off with the car running and saw no arcing, plugs have the blackness to them where you can tell the car was running rich..even though it acts as if its leaning out the more i lay into it.

Any ideas?

 

backfiring from intake or exhaust? could be valve adjustment or bent valve or ignition timing issue to name a few