Originally Posted by starnest
I'm guessing it is a balance problem. The crank (w/rods/pistons) and flexplate weren't balanced together. - AND/OR - The harmonic balancer is bad (or the wrong one).
The flex plate was tightened down ...off center. not completely flat[fitted]on the crank. before the tightening down sequence began.therefore it just broke out at the shown point hth No other reason to me.