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Thread: Weber Carbs

  1. #1
    Join Date
    Jul 2015
    Posts
    28

    Default Weber Carbs

    I am in the process of rebuilding the Weber carbs on my crossflow. The guy I bought the car from drove it without air filters and I poured handfuls of dirt out of them during disassembly. My question is; there are air passages on each bore that go to either side of the throttle plates & are regulated by a screw with a tapered end on it just like the idle mixture screws and have a small lock nut on them. They have these small white caps on them. I can't find any mention or a picture of them in Pat Braden's book & the University of YouTube seems to still be out on Summer break. Does anyone know what they do, what adjusting them will do & how to adjust them? I've attached a picture.
    Many Thanks, Kurt
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  2. #2
    Join Date
    Jan 2006
    Location
    Seattle-ish
    Posts
    1,031

    Default

    Those look like the air bypass screws. They are used to balance flow between barrels on the same carb and to adjust the location of the throttle plate to the progression holes at idle.

    -John
    Westfield SEiW
    2.0L Duratec
    Throttle Steer

  3. #3
    Join Date
    Apr 2008
    Location
    San Jose, CA
    Posts
    546

    Default

    John is correct. They are air bypass screws. If your throttle shaft is not twisted and your butterflies are setup properly, they should be all the way in. They are used for fine tuning during synchronization.

  4. #4
    Join Date
    Dec 2016
    Posts
    1

    Default

    -all of the above info. is correct. I have heard that they were added to help get multi carb. setup past emission testing. call me mike cain at 607 426 5598 if you need any more assistance.

  5. #5
    Join Date
    Nov 2013
    Location
    Midland, TX
    Posts
    456

    Default

    Haynes has a "Weber Carburettors" manual. https://www.amazon.com/s/ref=nb_sb_n...r+carburettors There's also a 1979-'91 edition.
    Westfield SEiW
    Done building, now grinning

  6. #6
    Join Date
    Jul 2015
    Posts
    28

    Default

    Hey Guys,
    Thanks for weighing in with all of the great information. Along with the carbs, I feel the need to clean my Uni-syn just to make sure everything is working properly. This is what make this forum so great. Being able to ask a question to which someone out there will know the answer.
    Thanks again, Kurt

  7. #7
    Join Date
    Apr 2007
    Posts
    197

    Default

    I do not wish to hijack this thread but does anyone have a good recipe for a "chemical soup" that will clean old carb bodies?
    I have yet to find one and do not like the idea of beadblasting Webers.
    Thanks and sorry if this is the wrong format.
    Dermot

  8. #8
    Join Date
    May 2016
    Location
    Houston, TX
    Posts
    8

    Default

    The carb in my generator got all plugged up with varnish-like stuff when I let it set for a few years in a HOT garage. Soaking it in denatured alcohol from Home Depot for a few days loosened it up. I was able to scrape out the thicker deposits with something non-metalic (a cut off zip tie).. I had to use thin piano wire to clear out some of the narrow passages in the carb body. I then flushed it with more clean alcohol. A turkey baster was used to force the alcohol into the narrow passages to flush them out.

  9. #9
    Join Date
    Aug 2006
    Location
    Pasadena, CA
    Posts
    1,605

    Default

    Quote Originally Posted by ottocycle View Post
    I do not wish to hijack this thread but does anyone have a good recipe for a "chemical soup" that will clean old carb bodies?
    I have yet to find one and do not like the idea of beadblasting Webers.
    Thanks and sorry if this is the wrong format.
    Dermot
    Bead blasting will surely clog the small passages and the bead stream will not get into the nooks and crannies anyway.
    The SeaFoam solvent is supposed to be a good carb cleaner for soaking or just regular carb and injector cleaner spray (use outdoors only) to quickly blast through. Both at any auto parts store.

  10. #10
    Join Date
    Mar 2009
    Location
    JOPLIN, MO.,USA, EARTH
    Posts
    285

    Default

    AUTOMATIC ULTRASONIC CLEANERs work great with carb cleaner liquid. Bought one at Harbor Freight. It even cleaNs out tiny jets in less than 50cc engines. It both heats and vibrates. The only problem is the size of it. LARGER WOULD BE NICE

    GALE

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