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94 2655 blown heads-gctid815744

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    94 2655 blown heads-gctid815744

    Ok guys here is the deal the 2 heads are cracked cant reuse them. Im looking into a good set of used ones. I just dont trust what the boat guy is telling me. The motor is a mrec 5.7 he says as lond as i use a head from any 5.7 it will work. Is this true? Id think that they may change of the yrs? With small things. Or am i wrong. Id think i would want to find 1 with the same numbers in the casting as mine are, or do them # not mean much? Any info would be great!

    Happy boating!

    #2
    Any sbc cylinder head will bolt up to the block, however you'll need info on the combustion chamber volume. Your new heads need to have that same volume or very close. They'll also need to mate up with your existing intake manifolds bolt arrangement.
    Dave
    Edmonds, WA
    "THE FIX"
    '93 2556
    Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

    The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
    Misc. projects thread
    https://www.baylinerownersclub.org/f...56-gctid789773

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      #3
      Correct bolt design, and your good to go, use marine gaskets.
      Be good, be happy, for tomorrow is promised to no man !

      1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

      '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

      Manalapan N.J

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        #4
        "builderdude" post=815746 wrote:
        Any sbc cylinder head will bolt up to the block, however you'll need info on the combustion chamber volume. Your new heads need to have that same volume or very close. They'll also need to mate up with your existing intake manifolds bolt arrangement.
        So when you say any sbc. That means it does not have to be marine, i can take one off a car? And if its the same bolt pattern if good to go. Or you mean any marine sbc? I just want to make sure i understand all the way. Thanks all for the great info already!

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          #5
          SBC = small block chev

          Yes a cylinder head from an auto will work but it needs to have the same combustion chamber volume as the ones that were removed and the intake manifold bolt angle on the center four bolts needs to be the same as the originals as well.

          Typical marine heads are a heavier casting than most autos.
          Dave
          Edmonds, WA
          "THE FIX"
          '93 2556
          Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

          The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
          Misc. projects thread
          https://www.baylinerownersclub.org/f...56-gctid789773

          Comment


            #6
            Agreed! Make sure they don't sell you a closed chamber head or a head that has been angle milled or anything before that would bump up compression. The newer vortex heads have a ramp under the intake valve that does help with intake fuel/air mixture. They are better heads but I am not sure if they have hardened seats from factory or not. Marine use is hard on valve seats.

            You also want to make sure that the heads have all the same accessory mounting holes in the ends if needed same as your old ones. I believe all the newer open chamber sbc heads do have them but I know some of the older heads don't.
            Doug
            1995 2859 -extensively rebuilt/restored 2016/17
            496 big block - Bravo ll leg
            The Doghouse
            Prince George BC

            Comment


              #7
              "Chingwow" post=815744 wrote:
              Ok guys here is the deal the 2 heads are cracked cant reuse them. Im looking into a good set of used ones. I just dont trust what the boat guy is telling me. The motor is a mrec 5.7 he says as lond as i use a head from any 5.7 it will work. Is this true?

              [color]blue wrote:
              No.....it is NOT true! This "boat guy" is in-experienced![/color]

              Id think that they may change of the yrs? With small things. Or am i wrong. Id think i would want to find 1 with the same numbers in the casting as mine are, or do them # not mean much? Any info would be great!

              [color]blue wrote:
              If (key word "if") we can trust that these cylinder heads have been correct from the get-go..... yes!

              Otherwise, we need to start with the piston profile![/color]
              Correct bolt design, and your good to go, use marine gaskets.
              [color]blue wrote:
              NO..... this is incorrect! Listen to what Dave says.

              Look at the casting numbers on the OEM cylinder heads.

              Now verify which pistons are being used.

              Post this info for us and we can further help you.

              In other words..... do not haphazardly change cylinder heads without first verifying which cylinder heads are correct for your engine and usage! This means not only verifying the combustion chamber volume, but also the runner volume, the intake manifold bolt angle, etc.

              There are many many many SBC castings out there.... make sure that you are replacing these with the correct ones. [/color]
              Rick E. Gresham, Oregon
              2850 Bounty Sedan Flybridge model
              Twin 280 HP 5.7's w/ Closed Cooling
              Volvo Penta DuoProp Drives
              Kohler 4 CZ Gen Set

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