After putting the new 360 in and discovering that it had a broken pushrod, we started it. Adjusted the timing and it now backfires through the carb. The carb is new so i was told that it has a bent valve. Sound right? How do i test to see what valve? Could i just assume it was the one that had the broken pushrod on it?And do i have to get the new valve at a machine shop or will the local parts store carry it? Thanks!