Re: 3.o omc
When I first got my boat, the motor was junk (along with most everything else).
I spent a long time at a local machine shop, and they were really helpful looking up specs for the engine trying to find replacement parts. I was reluctant to use something other than "the correct parts", but they were insisting that all the measurements for this part or that part were the same as the 350. Right now, I just cannot remmeber the specifics.
I would start off by trying to see what info you can get from the GM website. They still make the 3.0 (I think). I had previously found drawings and some tech info about dimensions. I know the outside dimensions specifically where there (clearances, mounting locations etc), but I think the bore, stroke, etc. were also listed. Otherwise, I might check for parts listed for "rebuild kits" and see if the same connecting rod is also sold for another application. I would check with a non-marine specific site, like TRW or someone else who deals a lot with engine rebuild kits. If the TRW rebuild kit for a marine 3.0 uses the same piston as some rebuild kit for a GM 350, then you have your answer. Now, Marine applications probably use forged or hyper-eutectic pistons and not cast ones (cast are the cheapest).
Or, you can hope to find a machine shop that is willing to research for you.
