[Rev]

This reminds me of a time just after I had installed new CC Magnum roller tip rockers on my 306. At that time I was using 351W heads that still had pressed in studs. After I had adjusted the rockers 1/2 turn down after 0 lash, I took it out for a test drive.

It seems that I did not tighten down the locking screw tight enough, at least on one valve. One of the rocker polly-lock adjusters loosened enough for the push rod to come out of the socket and hit the rocker arm just next to the push rod socket. This caused all manner of hellish noise as the extra force on the rocker actually pulled the stud out of it's pressed in hole, about half way.

Fortunately , nothing got bent. All I had to do was get the stud pressed back in and make damned sure that I tighened all the polly-locks down enough. I now after adjusing the valves and tightening down those allen screws, come back with a socket and give those adjusters a slight nudge tighter (not enough to twist off a stud please).

I'm just wondering if something similar could have happened in your case. If you have screw in studs or bolt down pedestals, there wouldn't be the give that my stud pulling out allowed. Something else would have to give. My guess would be a bent push rod and/or that broken rocker arm.

I don't know that this occured in your case, but it would offer a possible explanation as to what happened in your engine.

Rev