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Float height... does gasket thickness matter?

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  • Float height... does gasket thickness matter?

    I think I got the floats set nearly perfectly using the gasket surface as the reference point (Like the manual says). But I'm wanting to reuse a couple gaskets, and have a couple others that are a different material. I think that when I screw the float bowls down the gaskets will compress a little differently. Will that make a difference? or will one bowl hold just a tiny bit more than the others

    Thanks

  • #2
    You should measure from the carb surface the gasket sits on, not the gasket.
    Pat Kelly
    <p-lkelly@sbcglobal.net>

    1978 XS1100E (The Force)
    1980 XS1100LG (The Dark Side)
    2007 Dodge Ram 2500 quad-cab long-bed (Wifes ride)
    1999 Suburban (The Ship)
    1994 Dodge Spirit (Son #1)
    1968 F100 (Valentine)

    "No one is totally useless. They can always be used as a bad example"

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    • #3
      A little diff. in gasket thickness won't matter.
      79 F full cruiser, stainless brake lines, spade fuses, Accel coils, modded air box w/larger velocity stacks, 750 FD.
      79 SF parts bike.

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      • #4
        When the carbs are back in their upright position, the fuel level in the bowls is going to be set by how high the float is floating and that has been referenced from the carb bodies, even if you did your measurements from the gasket surface. It will not matter if there is an extra mm or four of fuel depth under the float.

        Next time you try to get your float levels balanced, though, the different gasket thicknesses will result in different operating float heights.

        The thickness difference between a couple of gaskets is not a lot, but I can attest that a 2mm difference in float height can make an enormous difference in performance. When I work on Tsunami's carbs a few years back, 2mm change in float height improved gas mileage by a solid 5mpg, and it got rid of a long-standing problem with black plugs.
        Ken Talbot

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        • #5
          All of the float heights should be the same correct? I feel dumb for asking but how did my floats get soo far off? I checked my hieghts the other day with a caliper and they seemed quite a bit off. The tang is pretty hard metal and I was afraid of snapping if off. What is the best way to bend the tang to change the float hieght? Also, since all of my floats are different, which one should I base the others on, or should I just set them off an average of all of the hieghts? And to answer your question: make sure you measure from the aluminum, not the gasket. That way with different gasketts, you are moving the bowls up and down, not actually changing the float level, just the volume of gas in the bowl.
          United States Merchant Marine Academy, Kings Point, NY
          If I can do it at 18 yrs old, anyone can
          "You know something, You can't polish a turd"
          "What are you rebelling against", "Well, what do you got?"
          Acta Non Verba

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          • #6
            Stick a small, precision screwdriver between the tang and the metal "frame" of the float and bend it to your will.
            Set all the float heights to the level recommended in the manual for your bike.
            One side of the float can actually be higher than the other, due to when the bike sits on the sidestand for years, the level of fuel in the bowl is sort of on an angle and the floats twist.
            Floats in bikes that have sat for years can do strange things. Carbs #1 and #2 usually have more sediment in the bowls than #3 and #4, due to the fact that, when the bike's on the side stand, the sediment in the tank settles to the left. The left petcock then lets more fine sediment pass into those bowls. Bikes that set for years... with bad petcocks... often have loopy floats. The two carbs on the side with the good petcock... the fuel in the bowls soon evaporate, and the floats hang down. The carbs on the side with the leaking petcock... the tank keeps filling the bowls as the fuel evaporates. The floats are always under an upward stress, and the float's tang slowly bends to accomodate this, hence those float levels don't match the other two.
            Too many variables to talk about... one no more viable than the other. Float levels do change... which is why there's the need to periodically re-adjust them.
            "Damn it Jim, I'm a doctor, not a mechanic!' ('Bones' McCoy)

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            • #7
              Thanks that helps a lot.
              United States Merchant Marine Academy, Kings Point, NY
              If I can do it at 18 yrs old, anyone can
              "You know something, You can't polish a turd"
              "What are you rebelling against", "Well, what do you got?"
              Acta Non Verba

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