Could oil restrictors have been installed? Old BBC drag racing stuff.

088's

I have a replacement set lined up, as well as two pistons.

Thanks to everyone for their help.

Got that engine all back together and running like a top again, less than 10 hours later the same cylinder on the port engine dropped the same valve seat and damaged that piston. you've got to be kidding me!!! these GM heads are junk.

Being the same cylinder twice my first thought is either the seat is not being installed correctly. Guess there is a chance the cylinder might be running lean but this would not cause it to drop the seat again so quickly. I would go back to the guy that did the head and find out why

It's on the port engine this time. The heads I just put on the starboard engine are fine. Its just crazy to me how these castings are so bad that they drop valve seats left and right. or i just have that bad of luck.

Dam dude. I thought my issue was bad. Very sorry to hear that.

I think this boat hates me. since buying last august, its gotten two new HP transom assemblies (leaking) new K planes and trim pumps (leaking) both drives gone through, both props refinished and balanced, all new engine mounts, couplers and drive shafts, new interior. Now this will make new heads on both engines and at least one piston per engine. on supposed "90 hour ago rebuilds" definitely didn't buy it with intentions of a full restoration but that's what its turned into.

You are having a run of bad luck, but you just don't hear very often about dropping a valve seat, and hardly ever being a fresh rebuild. Don't think its GM, still think its in the rebuilding side

Pretty sure the heads weren't touched. looks like they put bearings in and reused the stock heads. lesson learned. Next boat will not have anyone else's hands in the engines when I buy it.

a lot of those heads had the same problem,the eq 502 replacement head would be a much better choice imo and cheeper,i believe you can buy them complete ready to bolt on.