HELP, Mercruiser stern drive identification

Discussion in 'Sterndrives' started by jakeeeef, Dec 10, 2009.

  1. jakeeeef
    Joined: Sep 2009
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    Location: Hamble

    jakeeeef Senior Member

    I am in the process of being sold a project boat (deposit paid) with a Mercruiser outdrive, described as an Alpha 1. I am beginning to have concerns that it is a pre Alpha 1 drive unit, and therefore not worth anything like what I am about to pay for it. As the hull/ engine are shot, I've valued this package on the outdrive value so I'd like to find out what I'm getting.
    The seller is a really nice old guy who I don't want to offend by accusing him of subterfuge as I'm sure he believes it is an Alpha 1 so I don't want to try to trip him up over it, just get out of the deal if it's not what he clearly thinks it is.

    1) If it isnt an Alpha 1 what is it?
    2) Roughly what year is it?
    3) What is its value like in comparison with an Alpha1?
    4) How does it differ in terms of quality, reliability, reputation, longevity, re-power options, spares availability?

    Images attached
    Sorry for the picture quality, the boat and leg are a long way away so all I have are the internet advert images.

    As it's not connected to the boat I also wonder if it's the right drive for the gimbal bearing you can see in the transom from the old drive, so have also attached an image of the transom.

    Attached Files:

    • leg.jpg
      File size:
      41.5 KB
    • gimbal.jpg
      File size:
      3.4 KB
  2. jakeeeef
    Joined: Sep 2009
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    Location: Hamble

    jakeeeef Senior Member

    What makes me wonder is the lifting eye on the top cover.
    But might early Alpha 1s have had a lifting eye?

    I can't see the dated looking flutings down the side that earlier drives had.
  3. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    The drive is late 70's early 80's I Drive Not an Alpha which has a stronger lower unit. But an early alpha 1 lower will bolt up to the old 1 drive top box.
    They then changed the shape of the lower and the bolt pattern.
    The hydraulics are also the old high pressure low volume type.
    Parts could well be a problem by now.
    The top covers are interchangable but yes they do identify when they did the model change.
    The alpha 1 engine is also further forward in the boat than all the previous versions so inner transom bracket and the (uni) drive shaft different.

    The second photo shows a transom bracket from an even earlier package.
    That version is worth not much and had several different features ( or lack of) none of which you want. It might even be power tilt only version of its real old.

    The top (photo) drive on a V8 in a heavy boat is asking for trouble on an inline it will last for years if not moored. But you would still want to have it stripped and inspected
    Mercruiser clocked up their Millionth drive sold during that version in the late 70's
  4. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    It's an MR1, It fits the Alpha housing.
  5. sailabout
    Joined: Nov 2006
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    Location: Asia

    sailabout New Member

    Its clearly not a R nor an MR as the R which came first was the styling change to squared off housings, flat top cap, late style trim, aft end of the cav plate was almost flat not rounded like the one in the photo.

    The MR then had the ( much stronger) new style lower unit gears and drive shaft. ( housing same as the R to look at from the outside)
    Both these housings will bolt up to the old I drive as the old style was superceded by them.

    The Alpha's then got the new style lower unit housing ( with different bolt pattern, so top box different as well ) and water pump and integral oil reservoir etc

    So its a pre 83 drive and the lower photo is early 70's gimbal housing
    depending how early the gimbal housing is the drive in the top photo may not bolt up to it ( the lower photo is not clear enough for me to guess)

  6. CDK
    Joined: Aug 2007
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    CDK retired engineer

    At the time of production, Merc did not use the Alpha-1 designation because they didn't have the Bravo yet.
    And yes, it is a bit different from the later Alpha versions but is basically the same animal. The way the lower unit is attached is superior to the simple nuts and bolts of modern versions and the lifting eye they should never have omitted.

    For your motorcycle experiment I think it is excellent.
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