Off idle air screw Rochester 2Jet

Discussion in 'Other' started by Tripple7, Dec 3, 2021.

  1. Tripple7

    Tripple7 Well-Known Member

    Hello,
    I am currently rebuilding a Rochester 2GV carb for my '71 Skylark.
    I am wondering how to set the off idle air screw which is on the back.
    Any thoughts?
    Thank you
     
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Never heard of that. Got a picture?
     
  3. Tripple7

    Tripple7 Well-Known Member

  4. GSX 554

    GSX 554 Gold Level Contributor

  5. Tripple7

    Tripple7 Well-Known Member

    I already have the Bible, thanks.
    The problem is, that it tells me that there is no way to set that screw " in the field". Apparently it is a factory setting..
    But there should be a way.. can't imagine that the whole thing is garbage now just because I pulled that screw...
     
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

  7. Tripple7

    Tripple7 Well-Known Member

    Thank you Larry.
    Now I understand the purpose and function of the system better, but how do I set that screw properly?
    Turning it after initial tuneup would mess up my idle/mixture and idle rpm setting?
     
  8. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    You mean you just removed it without noting the adjustment?:) From what I read, it regulates the idle speed by regulating idle air bypass. There is a similar circuit in Q-jet carburetors but it isn't adjustable. Idle air bypass enables the throttle blades to remain nearly closed at idle. Opening the throttle blades too much at idle causes fuel to be drawn from the main nozzles.

    I would set the throttle blades just a bit open and play with that adjustment to get the best idle.
     
  9. Tripple7

    Tripple7 Well-Known Member

    Yeah, usually I make notes and Fotos of everything I take apart. Somehow I got carried away on that particular one.. Funny though that it seems impossible to find that information..
    Thanks anyway Larry
     
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    PM techg8. Ken might know.
     
  11. techg8

    techg8 The BS GS

    Yes it's an idle air bypass.

    I dont know a stock setting, though it seems like that would be in the service manual.

    Personally I would screw it all the way in which should eliminate the bypass air. Adjust your idle mix and rpm.

    If I had nozzle drip at idle then, i would open it up some and readjust idle settings. Repeat until you have no nozzle drip.

    Idle air bypass is more about throttle position at idle than idle mixture.
     
    Tripple7 likes this.
  12. Tripple7

    Tripple7 Well-Known Member

    Thanks guys,
    I will do that!
     

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