Quote Originally Posted by Bruch View Post
How's this for a Columbo theory? Motor heats up, top end is starving for oil, lifters are collapsing from low oil pressure.
Cam bearings heat up, cam starts to seize, key get sheared off and sprocket spins half a turn. Lifters are collapsed from low oil pressure so only one valve gets whacked, the one we hear in the video.
the odds of this happening are miniscual. so small in fact that i dont believe it. there is a more reasonable and realistic explanation as to how your cam gear got the way it did, and i'm guessing human interaction had something to do with it. i stand by what i said earlier. remove the head and have the valves checked.

make sure to remove the cams and inspect the journals. my guess is youll be looking for a different head. if you need a head, you can have this thing back on the road with $300 and a days work