Removing the Head revealed that this engine has been rebuilt before. The engine had hardened valve seat install at one time and also had bronze sleeves put in for valve guides. However, it appears as though one of the sleeves had slipped allowing the valve to close off center thus shattering the hardened valve seat. It also appears that chunks of the seat bounced around in the chamber for some time creating additional damage to the top of the piston and exhaust valve.
After cleaning things up a little…
Damage to the exhaust valve and top of the piston are clear.
|Missing Valve Seat
||Intact Valve Seat
Sort of hard to see but here’s a couple of the bronze sleeve that slipped…
Discovery of this damage makes it quite clear that the block needs to be taken to a machine shop to have new hardened valve seats and sleeves installed.