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105 Carburetter Jets

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  • 105 Carburetter Jets

    I have been tinkering with nets, as I was running rich.

    This is where I am now and wondered if anyone has noted their jet settings as a comparison. The technical literature is somewhat contradictory.

    Choke 40mm dia.
    Main..................190
    Compensating..112
    Economy...........210
    Idle.....................65

    With these jet sizes the car runs much more smoothly and has lost the flat spot coming off idle.

    The jets were.

    Choke 40mm dia
    Main..................190
    Compensating..230
    Economy...........230
    Idle....................65

    According to the Zenith literature the car runs on the compensating jet unless running flat out when the main jet comes into play, so my changing to compensating jet to one nearly half the diameter ( quarter of the cross sectional area)is the only difference.

    The Co meter that I have has come down from 14% to 7%, which probably isn't bad for a vintage engine. The carburetter is a V1.

    Comments welcome.

    Hmmmm.





  • #2
    Hi Dick,

    I cannot add anything at all but I am interested in your findings. My 95 is still in a thousand pieces, but is coming back together slowly. I have a carburetter which has been on the shelf for years, so your jetting might be helpful. Incidentally it did 13 mpg when I bought it 39 years ago. After a few years I took the 48v1 off and fitted a much smaller Zenith from a Ford Zodiac. No loss of performance but up to 21 mpg! This time I will really persevere with the original carb.

    James.

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    • #3
      Hello there,
      I just redone my 105's carb (Zenit 48V 1/2 / choke size 37). find below / attached the settings I have got (column ACT) vs. the to be jetting (column NOMinal). During the process (supported by the exhaust analyser) It became evident:
      - vacuum leak around the throttle (butterfly) stem --> rebushed
      - seperate choke system did not close fully - always "too much air" - affecting idling
      - in the process we enlaged the slow running jet from 80 to approx 100
      - also I had a huge vacuum leak due to a hole in the intake manifold where it rests in the exhaust manifold --> closed with "liquid" metal
      Now it starts, idles and accelerates very fine

      Hope this helps
      fred
      Click image for larger version

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      • #4
        Dan Nicholson has spent a lot of time making different jets and road-testing on my AV105. This is what he has come up with:
        Main 190
        Compensation 95
        Slow running 70
        Eco 220
        Mine is a V1-2 carburettor with 37mm venturi.
        He also discovered that the camshaft is a BA105, re-profiled to give a later opening time of 10 deg BTDC with an exhaust cam that gives a slightly higher lift and longer duration. Clearly it has been modified in the past - my car has been raced and rallied throughout its history.

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