Hamilton 733 3 stage questions

Discussion in 'Jet Drives' started by mrtoybox, Jan 25, 2009.

  1. mrtoybox
    Joined: Jan 2009
    Posts: 3
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    Location: WA

    mrtoybox New Member

    I repowered with a 400 horse Chev. The top RPM is 4500. It is on a 19' Almar with a mostly flat bottom. Definitely not a Deep V. It revs right up to 4500 with no cavitation but the boat takes forever to get up on plane even when empty. When loaded with peopole and gear it really takes forever but will finally get up on plane. Is this the best I can expect from this old jet, or are there improvements I can start making
  2. nzjet
    Joined: Oct 2008
    Posts: 6
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    Location: nz

    nzjet Junior Member

    Hi there,
    your 773 jet unit should get your 19' boat on the plane in about twice the lenght of your boat with 400hp and the unit running correcty (providing your boat is not super heavy +2ton)
    If the unit is pulling 4500 trying to get on the plane then it will be cavitating, you need to pull the unit apart and check the space between the outer edges of the impeller and the wear ring on the housing.

    Take the impeller off the shaft and sit it inside the housing on the ground so you can see, it should be a snugg fit and check that the leading edges on the impeller are not blunt.

    check how much water your boat is pushing on the plane as well, at full speed the water should be breaking out from the chine about 1-1/2 meters from the stern otherwise you may need to make some trim adjustments.
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