Typicaily, chain wear as well as guide wear cause the inner drivers side chain guide to break and the chain carries the broken piece along and between the chain and the sprocket, causing the chain to skip a tooth or two, the cam cover to break and the valves and the pistons to collide.

The head needs to come off and the valves replaced. It's a big job. You could find a replacement engine.

__________________
Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.