The Joys of boat ownership. My buddies 42 Silverton cruiser had a small tick and a plug that looked like that after it lost power once the plug gap got altered. Still had 125psi and cylinder looked like new. Piston didnt look too bad until I pulled it out.

Seconds from Catastrophic disaster.

Yeah that's ugly for sure. I'm preparing for the worst.

Yep, still there as far as I know!

Update:

Pulled port cyl head off this morning.

There was valve to piston contact in 5 and in 7, with 5 being enough to put a ding in the top of the piston about 1mm deep. 7 just shows a "smudge".
There's clearly a lot more crusty stuff in and around the combustion chamber on 5, compared to the other cylinders. I believe I dislodged a piece of this and that's what hung the valve open, then bent the pushrod.

The exhaust ports of 5 and 7 have visible corrosion, which leads me to believe that everything started from leaky headers (a shocker, I know). I believe this was a time bomb and I cut the wrong wire trying to defuse it.

Pictures coming shortly.

Similar on my 502. Good cylinder pressure and completely surprised when Ingot the piston out.

Hopefully no damage to the rod.

I’m sure I have a guide plate laying around. Might be able to come up with a couple of valves too. The exhaust valves are Inconel.

What’s the head look like?

Is part of the seat torn?