Great thread. I read on here somewhere that the GM steel heads are good but you can gain some fairly easy HP by doing some head work. There is room for improvement and the heads are good enough to warrant it. Wish I could find the thread.

Randy, you can use an off the shelf cam grind and be in the ball park or you can call RMBuilder/Bob Madara of Marine Kinetics (New York) and have him get it spot-on the first time. He's done cam applications for several guys here on OSO, etc. with great results. For about $70 more, he will take all your engine info and come up with a custom on the spot cam for your application and what you want to do with it. Bob's number is 585-654-8583 EST.

Also, you were asking about the heads---the Merc 502 Mags came with a stock GM rectangle port head---have them checked out or you may even want to replace them because they are prone to cracking between the seats. It happens randomly and it happens a lot! So, before you spend money on any head porting, etc, you might want to think about that.

The 502 Mags came with all forged parts, but no roller rocker arms. What kind of exhaust system are your currently running on your boat with your engines??? Who wil be doing the machine work and assembly of your engines?

thanks
 

Thanks guys for all the good input, Inspector I will ponder the cam you have, also RM builders, Kamma I am currently running stock exhaust but want to move up wont be anything real outrageous though revolutio/stainlessM. havent started calling machine shops yet, any suggestions thanks again. Randy