I want to buy a 540 short block from the same company that builds my drag race mtotrs and build a blower motor . Looking for 650 to 700 hp on pump gas, but am getting conflicting info on this subject !!! Could someone please explain the differences. I am aware of the valves , the cam I assume should be different, the intended rpm range in a boat is obviously different , but what other major difference would there be . I assume all machine work tolerances/clearances would be the same . Thanks for any help ahead of time .

It seems the tolerances should be set up looser. Cams,Comp.
The "car" guys motors I have seen dont seem to last

That what I was thinking, a little looser on the ring gaps etc. because of the extended higher rpm usage. But I couldnt think of any other big internal differences . I know oil pan , flame arrestor , valve covers etc. but they are all external items . I just cant come up with anything else major internally . Thats why I am hoping somebody here can give me some help so I dont waste my money if it isnt going to work anyway .

This his been debated so many times, I have personally argued this with people around my local water. I set my ring gaps according to Total seal recommendations for blower motor, I set my clearances at .0025-.003, and use a 112 LSA or 114 LSA. Salt water applications will need brass in the water jackets for anything aluminum. I run mine in fresh water only, so that has not been a problem. For instance the only difference in a 500 HP and a 502/ 502 is the cam, slight compression difference and intake passages are brass lined. Go for it and you'll save yourself some serious cabbage over the,anything for a boat being twice as expensive, price.

I dont know...Jeffrey just smoked a brand new zz572..tight clearances. He had some work done to marinize them Dont know what....I am watching his experimant with interest.

I forgot the thread name - how is is working since he fixed that glitch - still running strong??

Hopefully people that know more than I do will answer this for you, but I have been told that to convert would require exhaust valves, camshaft, oil pan, head gaskets and changes in tolerances. Also, even aside from those things automotive crate motors are just not put together well enough to survive in a marine application. Even though there are some success stories that make it sound tempting, if enough people respond to this post I think you will find that most people will recommend not using an automotive crate motor. I have paid particular attention to topics like this on the board and talked to alot of people about about it because I have been considering rebuilding/replacing my engines for a while now.

I have not seen the thread for a few days....Must be good news !

I have two friends running 502/502's and they are still running fine 4 years later. This does not mean a thing other than what I see. Don't use this as a reference they may work great or they may be lucky I honestly have no clue!

If I did it I would at the very least change cams.

read this thread, good info to keep in mind with any hi-perf BBC

http://www.offshoreonly.com/forums/s...3&page=1&pp=20