What are the differences between the 502/425 and the 502/500HP(Carb)?

Are 502 crate engines still available?

Thanks!

Camshaft specs, valvesprings, intake manifold/carb and exhaust manifolds. Same shortblock, cosmetic differences. Yes they are!
Dennis Moore

The ZZ502 has aluminum heads also.

Ron

wheres a good place to order one of these crate motors?

try here

http://www.macmaster.on.ca/bbcrate.htm

www.offshoreperformance.com
give them a call.
I bought one from them in the spring for $4300.
There a hi-output marine version. I did a merlin intake with a 800 holley, gil exhaust.
Engine has run flawless.

Some of these motors specifically say "not intended for marine use". What needs to be done to them to make them "marine" engines? Also, I notice that the HP500's from Merc are rated to run on 87 octane and the motors in the link above all say they need 92. I would like to have a 502/500 that can run on 87. Is that possible?

Dave M.

I have a GM (automotive) crate engine in my Baja, it is the 425 hp 454 HO. I have not had any problems so far, I run 34 degrees of total timing with no pinging at all. I have ran some 89 octane when I had to and did not notice anything at all. Most of the time I run 91 if I can. corrosion is the issue from what I understand, also the water pump is defferent, my crate motor cam with the water pump and now it is leaking. Other information indicates that the automove water pumps can not handle the pressure of the sea pump.

Brian