First I would like to say thanks for all the help in a past few days. It turns out I have a 1992 502 mag Gen IV (mark IV) motor. so I am going to do a rebuild with roller rockers and new intake and carb. I am also going to install headers and better cam. Any ideas ? what would you guys use ? Engine builder ATECO in Northern Illinois is going to do all the work. They said a nice set of CMI 502 E Top headers , cam, rollers, and holly 850 carb would be really nice. What would you guys use ? Thanks again

It sounds like they're basically suggesting you build a Hp500 motor. It's a good motor and makes decent Hp.

What do you want to do with the boat? How much wrenching do you want to do to it every year? How radical do you want it to be? Do you want to leave the lower end alone, or is putting a new crank rods and pistons in it an option?

Sorry about that. the hole motor will be rebuilt. I don't want to wrench on it at all.

No problem.

If you want a reliable motor that you can drop in and not worry about for a few years the Hp 500 is probably a good motor to duplicate. The parts are super common and easy to come by. It's basically a 731 roller cam, roller lifters, dart intake, and 850 carb. You can use your stock heads or upgrade, depending on what kind of power you want to see out of it.

If you're down this far and you can afford it, I would drop the extra coin and make it a 540. It shouldn't cost all that much more, especially if you sell off your old rotating assembly, and you will have higher quality parts (H-beam rods opposed to I beams, and a tougher crank).

Are you planning on boring the block and getting new pistons, or re-using the old pistons/bores?

Bill at Ateco will set you up. Your motor is a 390HP version. Roller cam, roller rockers, intake, carb, and exhaust will really wake it up.

Bill built me a reliable 540 with 610 HP. He won't steer you wrong.

I really like my CMI headers, look, sound and performance

Ateco can build whatever you want. Its pretty easy to get 500hp out of a 502 with stock heads and 9.0 compression.
Let Ateco get your parts and all you need to do is discuss the options and how much you want to spend. Ateco is also a CMI dealer.

As for a cam,
I suggest you get in contact with Bob Madera (aka:"RM Builder"). He his very sharp and very well respected! He will ask you a ton of questions regarding what you want from the motor, what you plan on doing with the with the boat and also want to know flow numbers on the heads, drive ratio, prop pitch, intake, carb, etc, etc, etc....(Be ready to answer quite a few questions. He can also point you in the right direction on parts to match the valvetrain if needed). The end result will be exactly what you want from the motor. Mark

Sledgehammer, how much did a 610hp 540 cost you if you don't mind me asking?