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Thread: Twin 45 DCOE - one not fully opening

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    Pit Crew Decade Plus User MK1_Oz's Avatar

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    Twin 45 DCOE - one not fully opening

    Noticed today that one of my webers isn't opening fully but cannot see why. I use Sytek linkages although I think the bits on the throttle shaft are probably weber items - cannot remember.

    I have checked that at rest both carbs are fully closed. 1 opens fully but the other opens only 95ish%. I would say that the butterfly is still within the shadow of the shaft when looking down the barrel so maybe will not make any difference.

    The shafts appear to be in line and there is no flex in the interconnecting parts.

    Its got me. Just wondering if anybody else has seen similar???
    1970 Mk1 Escort Tarmac Rally Car

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    Re: Twin 45 DCOE - one not fully opening

    There should be a mechanism between the two carbs shafts to allow balancing / equal opening. But if the carbs have been vacuum balanced ? Maybe one pair were pulling more / less so the imbalance could be intentional to balance airflows!

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    Re: Twin 45 DCOE - one not fully opening

    I believe you are correct, as far as I can understand that adjuster in the middle that links the 2 carbs permits tge throttle of 1 carb to be adjusted independently or the other. In my case I could use this adjuster to ensure the second throttle shaft fully opens BUT this would also mean that the shaft on that second carb woukd open by the same amount when the throttles are shut I.e. it just moves my issue from the fully open to fully closed position.

    there must be some alignment issue causing the shafts to rotate on different plains (planes?).
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    Re: Twin 45 DCOE - one not fully opening

    They can't be both equally shut then have different fully open points if the shafts are connected unless there is some severe slack in the connection and the cable actuation is pulling unequally one side to the other? Maybe they aren't equally shut - one tight, one loose but seemingly both shut?

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    Re: Twin 45 DCOE - one not fully opening

    Remove the linkage on both carbs and check for wear on the mount and carb spindle.

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    Re: Twin 45 DCOE - one not fully opening

    Bent spindle...? pretty common

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    Re: Twin 45 DCOE - one not fully opening

    i had them both on the bench and they are indeed both fully shut. The linkage acts on one card with a tongue pushing the second open. Cannot see or feel any slack. Will investigate a bent shaft.

    The things you find when you actually measure and check the detail!!!!!!!!!! grrrrrrr
    1970 Mk1 Escort Tarmac Rally Car

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    Re: Twin 45 DCOE - one not fully opening

    Stupid question but are both Webers of the same type with 78 degrees (?) throttle plates?

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    Re: Twin 45 DCOE - one not fully opening

    Yes. A matching pair.
    1970 Mk1 Escort Tarmac Rally Car

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    Re: Twin 45 DCOE - one not fully opening

    Ok think I have this one nailed. I took the inspection covers off that cover the progression holes. Although they both appeared to be shut exactly the same they were not. I adjusted the throttle plates so that they were at the same point and viola....
    1970 Mk1 Escort Tarmac Rally Car

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    Re: Twin 45 DCOE - one not fully opening

    I'll make a believer out of you yet !

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    Twin 45 DCOE - one not fully opening

    The thing is , they should both shut tight independently. Check butterfly's seat fully in bore as if screws are tightened when open they won't always seat correct.
    Then they need balancing when fitted and running.


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    Re: Twin 45 DCOE - one not fully opening

    Thats what he's done, adjusted the butterflies.

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    Re: Twin 45 DCOE - one not fully opening

    :o

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