If his engine builder degreed his cam when he installed it he should of seen right away if the crank gear was in wrong.

My thought was the cam was never degreed. When I installed my crank gear wrong (many moons ago) was the last engine I built without degreeing the cam. A quick observation of the crank gear or of the dots line up will tell the tale.

I agree if the head gasket is wrong strange things happen with heat, as well if the lifters are slightly to tight it will take about that time to build full oil pressure, thus bent valve. But by the sounds of it are they trying to help solve the issue? Hope so its the right thing for them to do . Good luck.

Are you running a water pump or a crossover?
I also believe that this might have also contributed to my failures outlined in the earlier link.

It has an Edelbrock circulating pump. I checked the head gaskets when I was over there today and the coolant passages all seem to line up. They are adamant that the cam timing is set correctly and have pulled it apart and checked it. I'm honestly lost. They think it's due to the oily build up in the combustion chamber and resultant heavy carbon build up on the valves. The new Manley severe duty marine valves arrive tomorrow and they are checking all of the guides with the diamond hone. I just don't want this to happen again.

A machine shop not degreeing the cam on a performance engine? I'm with those who say find a new builder/machine shop. If the timing is out it would be obvious as soon as the cams degreed. Going off of valves opening when this one is closing etc, etc is bs. It doesn't take very long to check and be sure. Mechanical damage from piston to valve interference is based off of timing being off or the valves are sticking in the guides because they are to tight when the motor heats up. Gummy residue on the valves from old gas with in 5-10 minutes of run time?? Hmmm sounds interesting. I don't build automotive engines on a daily basis, but I do build racing motorcycle engines daily and have seen some old gas, methanol and nitro mixes. I've ran them on the dyno with the customer not knowing of the bad fuel and they run like crap, but don't cause mechanical failure. Unless it had a ton of water in the fuel and it hydro locked.

Long story short, two times and still the same problem = news machine shop. In my opinion.

My expierance,,the exhaust valve is a common one to stick and or smack a valve due its expansion when the valve is hot.. you really need to be their watching them this time when checking the piston to valve clearances..i like to see a minimum of .100 thou..

It would probably be in your best interest to get someone to measure the guide clearance, particularly on the exhaust valves. Check them for being concentric as well as several spots along the guide. I believe 0.0015 - 0.0017 is a good ballpark to be in, but you should verify that with some experienced performance marine engine builders. Lifter bore clearance is another measurement that is often overlooked.

I'm taking the engine to another builder to dyno it. The original builder thinks it's fine and I told him he better be sure because if it blows on the dyno he'll be fresh out of excuses. He assures me that he has double and triple checked everything and now thinks that maybe the oil was drasticvally overfilled because of a poorly calibrated dipstick. I guess we shall see.

I don't think he is going to run out of excuses sounds like he has a whole book of them!