I'm building a 1979 360 based 408 with a small Comp roller cam with a single bolt. When I put the thrust plate on I have tons of room for the cam to move back and forth but when I tighten the cam pulley bolt I lose all of my end play and it becomes hard to turn. It's been a long time since I built a small block but I seem to remember a spacer that goes on the end of the cam but I can't find mention of such a thing anywhere. What am I missing? Thanks in advance!