Have a 401 in my CJ7. On Sat. we went wheeling for about 2 hours when we stopped for a trail repair on another rig. Upon restarting the engine, heard a loud bang, and the oil breather blew off the engine. Also blew out the valve cover gaskets on both sides.

Repaired the covers and installed new gaskets on the trail. Engine started up fine and ran perfect for another 4+ hours of wheeling. Started again at home on Monday.

My question is, what kind of damage may have been caused by this detonation. And what would have caused it in the first place?

Thanks