I have a brand new marine 350 on my DD boat. it fires up and runs great. If you ease into it until about 1500 then stomp it it will build power to 3k fast and easy but if you stomp it from idle it backfires through the carb its a new holley 390 2 barrel and it does have a safety so the power valve doesn't blow when this happens. I had the jets increased, bigger squirter and put a 50cc accel pump on it. I wasn't there but the mechanic triple checked timing and adjusted the valves. Im wondering if a different accl pump cam profile might straighten me out. I ordered them and they should be in today. currently it has a black one that came on it. Does anyone have a recommendation on what color I should use? From what ive been reading the position 1 is for a quick squirt for off the line and position 2 is later.