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Leaky Fuel Line Connections

Discussion in 'Technical Q&A' started by docweed, Sep 9, 2005.

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  1. docweed

    docweed Formula Junior

    Dec 8, 2004
    452
    Morgantown,WV
    Full Name:
    Chuck Stewart
    #1 docweed, Sep 9, 2005
    Just finished a rebuild on my 308 carbs. Replaced all the fuel line connection gaskets (both banjo and filter screen) with the fiber washers that came with the kits. At first no leaks but as I worked to equalize the carbs I started to see leaks at the connections. Noticed the the fiber washers needed retightened as they seem to become compressed with function or heat. I don't want to over tighten but I get the leaking stopped and they start again. Removed several of the fiber washers and replaced with the old copper ones that helpped but still some leaking. Tried some Non-hardening Form-a -gasket but still leaking. Would the teflon tape help and is there a tape that will work with gasoline? Any other suggestions? Appreciate any help.
     
  2. cavallo_nero

    cavallo_nero Formula 3

    Nov 3, 2003
    1,707
    colorado
    Full Name:
    Giovanni Pasquale
    #2 cavallo_nero, Sep 9, 2005
    i have had great luck with the aluminum (or copper) washers for teh fittings. no leaks at all. the aluminum works best i think, got em from the dealer
     
  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,806
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #3 Steve Magnusson, Sep 9, 2005
    Last edited by a moderator: Sep 7, 2017
    I think you're right to be concerned about "over-tightening" the fittings, and you should support the top cover casting side so that it doesn't have to resist the whole tightening moment by itself -- it's not a high-strength casting.

    The problem with re-using the Cu or Al washers is that they become strain-hardened after the first use (crushing them actually raises their hardness and yield strength) -- you need fresh, soft (i.e., fully-annealed) ones for the best sealing behavior.

    If you have trouble finding them, Global Metrics in Belmont, CA can supply either the W60 (solid Copper) or W63 (solid Aluminum) sealing washers -- just give them the ID x OD x thickness dimensions (in millimeters) that you need (and you can always add a handfull of the W60 22x27x1.5 Cu washers for the various oil plugs on your 308 to your order to help make the shipping costs make better sense). The attachment shows the sizes of W60 Cu washers that they offer, but I'm sure they'll have them in the W63 Alum type too.
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  4. docweed

    docweed Formula Junior

    Dec 8, 2004
    452
    Morgantown,WV
    Full Name:
    Chuck Stewart
    #4 docweed, Sep 9, 2005
    Thanks guys. With that info I'll try to hunt up some new sealing washers. FYI the guys that restore old steam and hit & miss engines will anneal the copper washers by heating them cherry red then quench them. As you said Steve they are stress harden and annealing will soften them again. There is some disagreement though as to what is the proper way to quench them. Some say quench immediately, some say just bench cure, and some say it doesn't matter which way. Do you have any experence in that area? I would quench immediately to soften but I think different metals react differently. I'm going to fine new ones. Thanks again.
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,806
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #5 Steve Magnusson, Sep 9, 2005
    Engineering references that I've come across report that the final hardness of Cu alloys is not dependent on the quench rate so I'm in the "doesn't matter" camp (but I always water quench when I'm forced to resort to reannealing Cu pieces just to speed things up -- and the results have been good). My choice, too, is to buy new whenever practical rather than reusing -- to much time hassle to reuse.
     

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