Two part question:

I'm looking to up grade in size, what hours on an engine should I be looking at for a rebuild? I don't want to buy a boat then shove more money per engine on a rebuild.

Secondly, what should be done on a rebuild/refresh? And "typically" what approximate hours does this "normally" need to be done, if I buy a boat I want to see what was done recently or anything major was skipped just because he/she is selling the boat.

thanx

Not really a simple answer. When I bought my boat it had a mere 20 hours on a complete rebuild with new heads. Both motors didn't hold together for 10 hours under light use. All depends on the builder and boater. I've seen stock and high performance motors last from 30-1000hrs.

IMO - rebuilds at 500hrs on a high performance application aren't a bad idea. When buying used the best you can do is a leak down and oil sample test.

All of your questions depend on what engines you're looking at.

What he said......boring but reliable 454/330's if treated nicely can go 1000 hours before needing a rebuild. You get into Merc blue motors or blower applications and you're looking at much sooner.

502's mpi and 500's efi don't think I can afford boats with 525's

On 502mpi's, my feeling is 400-600hrs needs a valve job/top end refresh. Will probably need a full rebuild in the +/-1000hrs range.
500efi's, probably +/-300hrs for the top ends and +/-600hrs for full rebuilds.

I would say these numbers are for engines that are maintained well and run like an average pleasure boat. Probably 15% below 2000rpms, 70% between 2000 and 4500rpms and 15% above 4500rpms.

Awesome this is exactly what I was looking for.

thanx