I'm running a 63 425 in my A roadster with an ST400 trans. During the engine rebuild, I found out the crank was bad and replaced it with a dynaflow crank. My problem is the starter is grinding on the flexplate. It almost sounds like it's not disengaging. I did space the starter out now to 9/16". I've heard 1/2" to 5/8" before. Could it be that I'm not out far enough? Or is there a combo issue here?