Carburetor gasket replacement

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  • gregsails
    Senior Member
    • Sep 2013
    • 105

    Carburetor gasket replacement

    It's been 5 years since I had my late model, 4 screw carb apart for cleaning. I'm looking at it and for whatever reason last time I dressed the big gasket with Permatex Aviation gasket maker. Don't remember why. Is that necessary or should I use the gasket only?
    Thanks
    Greg C30 sail 694
  • GregH
    Afourian MVP
    • Jun 2015
    • 598

    #2
    Just the gasket should be enough if the two faces are flat/true. maybe you added some as a belt & suspenders thing? Or maybe you had a small air leak ( especially at the pointy end where the 5th bolt is now used)?
    Greg
    1975 Alberg 30
    sigpic

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    • GregH
      Afourian MVP
      • Jun 2015
      • 598

      #3
      hey, its the Cdn Contingent this morning!
      Greg
      1975 Alberg 30
      sigpic

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      • Dave Neptune
        Afourian MVP, Professor Emeritus
        • Jan 2007
        • 5099

        #4
        No permatex, bare gasket only. If the faces have a gap, lite honing using fine "wet-dry" on a flat surface like glass will help. The part that needs to be sealed inside is the "emulsion well" in the center of the bowl or the carb will be way off.

        Dave Neptune

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        • gregsails
          Senior Member
          • Sep 2013
          • 105

          #5
          Thanks Dave. Glad to see your still active

          Comment

          • Al Schober
            Afourian MVP
            • Jul 2009
            • 2031

            #6
            Agree that sealant should not be required.
            Having said this, I usually put sealant on one side just to hold the gasket in place during the next disassembly. Transmission cover, I bond it to the cover. Valve cover, ditto. Makes reassembly much easier.

            Comment

            • gregsails
              Senior Member
              • Sep 2013
              • 105

              #7
              Dave Neptune

              So Dave, I fact I do have some worping between the faces that I will try to minimize. What is the emulsion well? And why is it so important?
              Thanks Greg

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              • Dave Neptune
                Afourian MVP, Professor Emeritus
                • Jan 2007
                • 5099

                #8
                The Emulsion well is where the fuel is first started mixing with air. The vacuum of the engine sucks air into the well to mix with the fuel from the main jet before the "mix" is directed to the venturi in the throat of the carb to be further mixed with the air going through the carb. This "mix" must be correct for proper burning in the cylinders.

                The "E-well" is the protrusion in the center of the float bowl toped by the "air jet" that regulates the air going into the well to be mixed with the fuel (the brass tube with holes in it) from the main jet just below the well. The top of the well must be sealed via the Hole in the gasket to control proper fuel mixing. The air for the well that travels this path is drawn from the throat of the carb to balance the carb mixing across the RPM (load) band.

                If it leaks the carb will not work properly causing loss of economy, smooth running and power.

                it is why you should always use a fresh gasket for a good crush of the gasket creating a proper seal. Check the old gasket for a full circle indentation in the center meaning it was a good seal.

                Dave Neptune

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                • JustinAlenScott
                  Senior Member
                  • Oct 2022
                  • 16

                  #9
                  Thank you, Dave, for talking me into buying a new gasket. Although I may reuse the flange mounting gasket. Stay tuned for my upcoming carburetor question.

                  Comment

                  • Dave Neptune
                    Afourian MVP, Professor Emeritus
                    • Jan 2007
                    • 5099

                    #10
                    Justin, a trick on carb gaskets that I use when tuning a carb IE disassembling and assembling in a short period of time or when I can't get a fresh one right away is as follows. Spray with WD-40 until wetted, place in a baggie and let it sit in the sun for an hour or so. The gasket will "swell" a bit and can be re-used a few times. However for rebuilding and assembling for continued use I always try for a new gasket.

                    Dave Neptune

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