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Thread: GM crate engines

  1. #11
    If you read mercruiser bulletins about these engines they reccomend not idling under 1300 rpm for any amount of time because reversion may occur. Someone with knowledge of GM could confirm this but I would have a hard time believing they build the same short block with different clearances for diff' uses. Also marine cams are usually ground on a different centerline to have less overlap?

  2. #12
    I have a '96 502 shortblock for sale with less than 25 hours on it. $3150.00 to closest Yellow Freight terminal. E-mail me at if you are interested.

  3. #13
    Does anyone know why I shouldn't put the 502/502 GM crate engine in my jet boat as is? Yes, because you should put one of these motors in your boat instead.
    I have a GEN V 502 in my boat and I really like it.
    Good luck.

  4. #14
    I'm just a little curious as to what makes their cam specs so different than a marine cam??? There are subtle differences right? But how would that create reversion as to a "marine" cam not making any???The marine cam will typically not have as much overlap. Overlap is the time both the exhaust and intake valves are both off of the valve seat some amount. Basically the exhaust is still letting out spent gas but the piston has started back down on the intake stroke with the intake valve open. So if you have some residual water hanging out in your exhaust header and it's close to the exhaust port, the vacuum generated by the downstroke of the piston can draw some of that water back into the cylinder through that still open exhaust valve. That's why a lot of the race headers dump the water further down the riser then a standard set up. While a small amount of water can cool the charge and surpress detonation, ala water injection, water is one of the few liquids that does not compress. Piss it off and try to compress too much of it and the loser will be your connecting rod eek!
    [ November 28, 2002, 07:40 AM: Message edited by: Craig ]

  5. #15
    I've run the 502/502 in my boat for three seasons now. It has over 200 hours of use on it and no sign of trouble. Running Gil Offshore manifolds and full MSD ignition. 16 degrees initial advance and 39 degrees total timing. Boat runs at 5200 rpm all day long. I like the idea of the 572 and may consider it when pricing is released next month. If its reasonable I might have a 502/502 for sale.

  6. #16
    I looked at the crate motors last year and also was curious about "Not intended for marine use". I emailed them "" and asked if they offer any marine engines. They replied "No we do not offer any marine engines, but we sell engines to boaters everyday!" I ended up getting a sweet deal on a SBC from

  7. #17
    Sorry took so long to get back to ya-gone over Thanksgiving week. I used a Milodon pan that was 7 3/4" deep.The stock pan was 1/2" to deep. This pan gave me 1/2" clearance. I bought it through Jegs. Used ones are hard to find for the Gen 5 and 6 engines..........Bill

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