When I drive my car (350, stock dished pistons on a stock bottom end, RPM Air-Gap intake, 750 holley, vortec heads, msd ignition, comp 268XE cam, 1/2 fuel line with a holley black fuel pump 150ish GPH) on the street, just cruising, i hear and feel a pop or backfire. Under acceleration it works fine. When we built the engine we didn't have it bored, just re-ringed and the top end is completely new except the carb. It is the second carb we put on it. We got this one from a race shop we go to and they both said it was a perfectly good carb when the gave it to use. I know a 750 is alittle big but would that make it pop? is there something that makes it pop that I'm not seeing? I don't really know what to ask, I guess just looking for some suggestions on what to check.