mercruiser 502
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mercruiser 502

  1. #1
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    Default mercruiser 502

    Just wondering if anyone knows any info about the merc. 502 shortblock. Would it be an okay shortblock for a jetboat? What gen block is it? 10.2" deck? Its got a factory roller cam, would any replacement roller cam work or is there something special you need to look for?

    thanks

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    Merlin heads or early block heads won't work with this block will it?

    Also, I'm thinking single 850ish carb would be good, I know this is a discussion within itself, but for a pleasure jet boat would you go single carb with an edelbrock air gap intake?

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    sorry about these questions seeming silly or rushed, I have been kinda frantic to find parts now that I finally have a little cash, and there's a 502 shortblock for sale, and I want to get everything quickly so I'm trying to figure out what works and what doesn't.

    Should/could this be moved to the on the Dyno section maybe?

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    Senior Member Brendellajet's Avatar
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    if its a 502 its probably not a Mark IV block, so you will want to research the issue of bolting a different era of cylinder head on it. Pretty sure there is a simple modification that needs to be made to the head gasket, but you have to know what block it is first. The only 502 I have seen was a Gen VI, but Im pretty sure there is a Gen V 502 as well.

    For now, put the money away and figure out what it is that you need to make that combo work. There are lots of deals out there on motors with decent parts...
    "He is a lover, not a fighter. But he's also a fighter, so dont get any ideas."

  7. #5
    Screamin SeaMonkees Schi-502's Avatar
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    Check the cast # on the rear, R/H side and ost it.

    I've got a ZZ502, gen VI in a 22' Schiada. Berk 12jg, SS "A".
    Max rpm, 5200, max speed on gps, 65 at sea level.
    Picts in Boat spam under '74 Schiada, jet.

    After edit...
    I went from an 850 cfm, Vac Sec, elect choke to an 800 cfm, Vac Sec, elect choke. Better throttle response and fuel economy.
    $.02
    Last edited by Schi-502; 05-27-2010 at 09:45 PM.
    Loose, the Dogs of War!

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    thanks for your input guys.

    I know it says 8.2 on it, I can look for more when I see it.

    and I really can't think of a reason why I should go with a tunnel ram on a taylor ss, single carb should give me all the go I need, with better fuel economy right?

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    really need some help on which cam and heads I'll need

    Thanks guys1

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