I have 2 1999 502s with brand new heads all new hardware 2 weeks ago with about 3 hours on motors the starboard engine snapped a rocker arm stud lucky no other damage replaced the stud. got the boat back in the water Saturday ran for about 1 hour and the same thing happened on the port engine . Any ideas as to what the heck is the problem

There's alot of knockoff junk on the market these days. Rockers, cranks, rods, etc. If you order parts that are house brands from Summit & Jeg's, they're probably Chinese. IIf you didn't take them yourself out of the box that had the known name brand printed on it, I'd assume the worst anbd replace them with SRP or an equivalent. No-name rockers & valve springs are going to cause you the same problems.

Did you change the cam or rocker arms. Sounds to me like the slot in the rocker arms is not long enough and they are hitting the studs. But I also agree with Chris, lots of junk out there.
Dave

Did not change the cam and rocker arms are suppose to be new,all the work has been done by a performance boat shop. I will have to ask about them who made the parts.

sounds like rocker hitting stud or junk studs, as already stated, arp's, crane roller rockers, tall valve covers, problem solved.

sounds fishy...did you look at the rocker travel ? ck for bind, bottoming out, etc, broken a lot of BB valve train parts but never a stud, and you 2 ?? maybe they are just garbage, but somethings up for sure !! Rob