The car runs great, super consistent at the track, but after every pass when I lift off the gas the car back fires. I took the carb apart last week but didn’t find anything wrong. I went ahead and removed my power valve (just to eliminate a variable), plugged it and square jetted it. Raced Saturday….still back fires (but runs great). I found if I take my foot out of it slower, or give it part throttle it usually helps (or stops it completely). Plugs look a bit black as usual, but they always do…for some reason my car gets the best ET/MPH this way. New plugs always start out a nice tan, but get darker as they age (they look like it is too rich, but it runs well so…???).

Carb is a 650dp with a Proform main body (making it a 750), jetted 90 square, on a 410 stroker, pump gas.

Any ideas on what it could be? By the way, this just started at the end of last year, only raced a few times since.