Just had engine rebuilt a 1996 454 chevy with B&M blower. Broke in and Dyno'ed by dyno shop. Made 620 HP @ 6000 RPM. Ran for about 10 hrs and then didn't start, no spark. Replaced Coil, nothing, replace MSD ignition Control Module, nothing. took off cap and rotor not turning?? Pulled MSD 8560 distributor and the melanized gear was ware all around and teeth gone on one side. In Process of talking to my machinest but he seems to be at a loss and I donot want to pull the engine again.. Comp roller marine cam calls for the melanized gear which I had. I am troubleshooting now with a bronze gear, knowing it is not the right one but softer so I can figure this out quicker (that is the thought anyway). I sprayed with graphite and turned engine over 3-4 rotations to see wear pattern and this is what I got. The dist was all the way down (no shims), not bottoming out, and this is the wear pattern (see pics). Any ideas??

You will need to zoom in on pics to see.

Cam is probably walking in the block.

96 454 should be a gen 6 with a step nose cam&retaining plate to keep the cam in place.