Another theory:
S&S changed the specification of the camshaft pulley nuts from a flanged serrated type to a flanged, non serrated type intended to be used with Loctite. I'm not sure when this change took place, but it's documented in their literature as well as in a post or two on this forum.
The specification change was no doubt for a reason, perhaps that reason being the nuts were not sufficiently keeping the pulleys immobile relative to the camshaft?
Would be interesting to know which type of nut was used on the damaged engine.
