Blue Thunder, The motor has about 140 or so hours on it. So you think I have a water issue? I pressure checked the CMI's. They have the silent choice divertors. Do you think I could be getting some reversion? This is a factory built motor and I believe the cam is a Crane # 132561 duration is 228/235 at .050 with 530/551 lift. If it was water woudnt the exhaust valve be the one broke or does it not matter? Sorry for all the qustions. Thank you

Don't try and be lucky twice in a row!
 

Intake valves do not really run hot or lean in an engine like this and the water from exhaust if coming in, comes in on the exhaust valve , not the intake and seat rusting and such is usually very visable.
My guess is just either an old tired set of valves or valves of very poor material that just caused the valve to crack and fail. My suggestion is to get all those valves out of the engine and install a nice new set of stainless EV8 intake and exhaust valves, Manley, Rev, Howards, etc. make some good sets for reasonable dollars.
Don't take the chance of another valve failure, you were really lucky you did not loose the whole cylinder or even block!!

Best Regards,
Ray @ Raylar

The pics do look steam cleaned to me. The reason you need to replace all the valves (severe duty manley on intake, faria inconnel on exhaust would be my preference) is because the better valves can take a bit of water spray from slight reversion and not get brittle. Plus the other rigors of marine engines (high heat particularly in the valve train) require the tougher valve. Raylar is right on with his advice as always. You really need to do all the valves and also make sure the springs are fresh. Pounding on the seat from the lifter coming off the cam can cause this too. The valve is cooled while on the seat. Weak springs result in less seat time for the valves.

Did any of the other cylinders look like this? Check to make sure you did not have a head gasket leaking water into the cylinder. That could explain the broken valve and the score marks if it was washing the oil off the walls. If it had ingested something you would see signs of it on the top of the piston, and it looks like you have the entire piece that broke off the valve.