i pulled the carb apart, no issues with power valve or jetting. it is a holley 870 avenger. verified jetting for this carb etc..

however the power valve did have 2 gaskets on it. I pulled the PV and it had one on it and one of the metering plate. thinking it split i inspected it and compared it to the 1 replacement i had. I had 2 gaskets from the factory. I hope it is supposed to only have one. Thats how it went back.

thinking now maybe it is time for a cam swap. after talking with my friends, many of which are professional gear heads we have tried and ruled out just about everything that could cause this backfire.

The one thing left is maybe the comp cam custom grind they did for this engine is messed up??? shruggy

I also want to get a little more vacuum back into the engine so I am thinking if something sub .500 lift. mopar 484 cam?

id love to see this motor make some decent power, right now it does not. it is slow, weak and underwhelming. id think a 10 to 1 383 with stealth heads, harland sharp rockers, 1 3/4 headers, m1 intake and 870 vac carb would be snappy and fun. the car has 3.91 gears and a 26" tall rear tire.
I know 400 is very attainable from a 383 of this build- do you guys think a mopar cam is the way to go?