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Thread: Alpha drive question

  1. #1
    Join Date
    Jan 2011
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    Alpha drive question

    I need a Alpha 1 outdrive for a 86 18 Classic with a 300 Tempest. Does anyone know what gear ratio it came with? Is that the ratio I should replace it with or does another work better? Its was spinning a 21P prop , should I be able to go to a 23 with that set up? Does it matter if I put a Gen 2 Alpha on it?
    Lastly does anyone one on here have a good used Alpha for sale that will work for me?
    Thanks Tony

  2. #2
    Join Date
    Jul 2006
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    The 300 Tempest was a high performance engine produced by Mercruiser from 1985-1986. It was around 300 hp, but most think this was a little overstated and was around 270. An Alpha with a 1.5 ratio should be perfect. Welcome aboard.
    1979 Donzi Criterion
    1997 Classic 16
    2007 G3 w/ Yamaha 90 hp jet outboard
    Jackson Hole, WY

    Just my .02, which in this economy, is only worth .01, and actually is less than that since my original .02 isn't really worth .02.

  3. #3
    Join Date
    Nov 2003
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    I don't think you can easily bolt up a newer Gen II outdrive to an earlier Gen I gimbal assembly.
    George Carter
    Central Florida

    “If you have to argue your science by using fraud, your science is not valid"
    Professor Ian Plimer, Adilaide and Melbourne Universities

  4. #4
    Join Date
    Jul 2001
    Rep Power
    PM Rootsy he has done that upgrade, he can tell you what you need to do. About the 300 Tempest/Alpha package my 22 came that way it would swing a 21 heavy cup to a tad over 61mph. It had a much better cam was a 4 blot block with good rods had a very pronounced lop, I think it was rated about right.
    No matter what your beliefs are "GOD BLESS AMERICA"

    Semi retired marine tech over 50 years in the biz.

  5. #5
    Join Date
    Aug 2011
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    Tempest 300 with Alpha SS

    My 1986 Kavalk 19 came with this package.Glass deep Vee hull mahogany deck 2700 lbs 23 degree Levy type bottom,71 mph 23 ' pitch at 5150 at 2.5 " X dim and 75 mph with 25 " pitch on Alpha SS at close to 5" X dim. Did not look at the tach.My point is that the Tempest has more than 300 HP and does it ever sound and run sweet.My 2004 22 C runs Bravo with 6.2 barely touches 60 with 23 " pitch .But then the A/V plate is only 1/2" above the keel
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