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Thread: Fuel injection or carb for my repower?

  1. #1
    Join Date
    Jul 2016
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    Stockton, Ca, USA
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    144

    Default Fuel injection or carb for my repower?

    I am re powering my 1961 50' Chris craft coni and want others input. It will be getting new transmissions as well as I won't use the old paragons. To much to rebuild.

    The two engines I am leaning towards for this are both mercruiser 383 mag strokers. One with multi port injection and the other carb.
    Both have the same power output.

    The delima is this. Currently with the old engines one engine is right/reverse rotation. If I buy the carb motors I can order one in a reverse rotation configuration for an extra $1000. And that's if I can find a transmission that does reverse rotation and is 2.5:1 reduction.

    If I buy the mpi engines they are $500 each more and don't come in reverse rotation meaning I would have to reprop the port side. That would cost around 2 grand.

    So the the price of the carb engines is the same as the mpi when you add the cost of the reverse rotation engine in, but may have added cost to re-prop and may require a fly by wire throttle system.


    Thanks for any input.

  2. #2
    Join Date
    Jan 2008
    Location
    Lynden, Wa
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    3,522

    Default Re: Fuel injection or carb for my repower?

    Buy the two mpi engines. The transmission on the one side can be fitted with an additional gear to reverse the rotation.
    There's the plan, then there's what actually happens.

    Ben Sebens, RN

    15' Welsford Navigator Inconceivable
    16' W. Simmons Mattinicus double ender ​Matty

  3. #3
    Join Date
    Jul 2016
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    Stockton, Ca, USA
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    144

    Default Re: Fuel injection or carb for my repower?

    I have heard this many times but have yet to find a transmission company or dealer that knows anything about the reverse geared transmission you speak of. Any info on that?

  4. #4
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    Jul 2016
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    Stockton, Ca, USA
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    Default Re: Fuel injection or carb for my repower?

    a zf63a can just be run in reverse apparently so problem solved there. Now to sort out the throttle issue and find out if i can go mechanical or if i need to use electronic.

  5. #5
    Join Date
    Jan 2005
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    Deepest Darkest Wales
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    Default Re: Fuel injection or carb for my repower?

    Is it true that current US fuel has a nasty habit of gumming up carbs?
    Creationists aren't mad - they're possessed of demons.

  6. #6
    Join Date
    Jul 2016
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    Stockton, Ca, USA
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    Default Re: Fuel injection or carb for my repower?

    Yes it has 10% ethanol which as anyone with high school chemistry knows is really bad as it mixes with water then separates and rusts out fuel tanks, gums up everything, dissolves rubber...... Ethanol has cost the boating industry billions I would guess.

  7. #7
    Join Date
    Oct 2000
    Location
    Padanaram, MA USA
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    9,625

    Default Re: Fuel injection or carb for my repower?

    And the people in Iowa who grow the corn to make the ethanol love the idea.
    Using ethanol was said to conserve petroleum, but the amount of petroleum used in growing the corn, transporting it and converting to ethanol eats up most of that.
    Politics.

  8. #8
    Join Date
    Oct 2005
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    Belfast and Marshall Cove, Islesboro, Maine
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    1,929

    Default Re: Fuel injection or carb for my repower?

    Jim Conlin. It actually takes more than 1 BTu of petroleum to make 1 BTu of ethanol. But what it does for Iowa Congressmen? Priceless!!
    Beyond that, I think both Twin Disc and ZF make reversible gears.
    From my point of view, if you're going to hire someone to maintain your engines, get the FI; they burn less fuel/hp. If you're the motor guy, get whatever you understand best. Personally, I'd rather fool with an FI than a Carter 4-barrel.

  9. #9
    Join Date
    Jun 2015
    Location
    Graceville, Florida
    Posts
    157

    Default Re: Fuel injection or carb for my repower?

    Quote Originally Posted by P.I. Stazzer-Newt View Post
    Is it true that current US fuel has a nasty habit of gumming up carbs?
    Yes, if you let the motor set with fuel in the carb bowls. Of course, this takes months to accomplish, depending on the size of the pilot jet. That was a problem even before ethanol was added to gas as an "Oxidizer". Gasoline tends to seperate and leave deposits over time. All previous "Oxidizer" additives allowed this to happen also.

    However, if the jet isn't completely plugged up, fresh ethanol gas flowing through it will dissolve the gum and leave it clean again. Other "Oxidizer" additives didn't do that, so you had to remove the partially blocked jet and clean it manually.

    regards,
    Joe
    These days, everything I do is just "puttering around"

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