Backfiring through the carb?

I just recently built my first 350 sbc, when i try to flip the throttle open it backfires through the carb, it idles and revs up perfect but when i go to open the throttle fast it will backfire, this is in park by the way, timing chain is brand new, new cap and rotor, new fuel filter and pump, ive been asking around and others are saying its the timing or carb, im leaning toward the carb more than the timing although it could be off, but the engine starts up every time with ease and revs fine, the heads machined and new valves etc, valves could be another issue, i dont think they are 100% adjusted properly, the carb i have on the engine is edelbrock performer 600 cfm electric choke, i had installed my older 600 cfm performer carb and ran rough, so i know the new carb i have makes a big difference, also my spark plugs are dry but looks like they have a little soot on all 8 of them, open to any suggestions that may fix this problem, thx in advance everyone