Specs: 72 CST with '94 SBC 350 crate motor, quadrajet, electronic ignition, stock headers, air pump plumbed and spinning(working -don't know), dual exhaust. The damn thing starts quick - I mean real quick. Runs great as far as I'm concerned, with one exception...it backfires thru the exhaust like a beeattch when I coast, with a massive one after any prolonged WOT stretch. What should I target first? It never backfires during postive acceleration, steady throttle or idle. Other info, I haven't made any adjustments to the carb yet (it was a CA car near sea level and I live at 6,200 feet). Also the fan clutch is shot, so I'm driving the fan always.