440 wont start

i don't think the balancer moved i just tried putting back on the victor manifold that was on it when it was running just to see if that would change any thing and the same thing popping and backfires i've gone over the firing order atlest 20 times just to make sure it was right i tried putting cylinder 1 on tdc and that all seems to line up the rotor points at number 1 both valves are closed i can spin the push rods around easly i check all the other cylinders and the same thing push rods move easy when valves are closed i would say maybe the piston was coming up and touching the head but the spark plug gaps aren't crushed or anything like that an when i checked for tdc i could feel where the piston stopped i'm starting to think i might just have to put the old 906's back on and see what happens its not and easy task but every thing i'm tring isn't working