Avs secondary tuning ?

Fuel and Air Systems

  1. mbaird

    mbaird mbaird FABO Gold Member

    Messages:
    5,130
    Likes Received:
    2180
    Joined:
    Dec 10, 2005
    Location:
    boise, Id
    Local Time:
    1:18 PM
    What is the relationship between air door tension adjustment and cruise AFR ?

    I understand that when you mash the throttle the secondary butterflies and air door should be set for a seamless transition. But what about a steady cruise ? I am referring to a 60-80 mph cruise speed.

    If the throttle plates are opening but not the air door are the secondary jets drawing any fuel in ? or inversely if the air door is set too light is it opening before the butterflies and if so what are the effects ?

    Which one creates the draw of fuel ?
     
  2. 318willrun

    318willrun Stomper 4x4... we kept energizer in business

    Messages:
    10,939
    Likes Received:
    10106
    Joined:
    Sep 13, 2013
    Location:
    I'm here
    Local Time:
    2:18 PM
    • the secondary butterflies shouldn't be open at cruise, even at 80 mph.
    • vacuum opens the air door, but the air door allows the vacuum to first start the fuel flow syphon
     
    • Agree Agree x 3
    • Like Like x 1
    • yellow rose

      yellow rose Doctor of Thinkology.

      Messages:
      18,470
      Likes Received:
      14519
      Joined:
      Jun 19, 2015
      Location:
      Living on the razors edge
      Local Time:
      12:18 PM

      Exactly. This is not a vacuum secondary carb. It has mechanical secondaries, just like a Thermoquad or a quadrajet.

      The throttle opens the secondaries and when the air speed is high enough to overcome the weight of the air door and the tension spring, it opens and you have air flow through the secondaries.
       
      • Agree Agree x 3
      • Like Like x 1
      • 1969383S

        1969383S FABO Gold Member FABO Gold Member

        Messages:
        4,780
        Likes Received:
        1945
        Joined:
        Jan 8, 2012
        Location:
        Cumming, GA.
        Local Time:
        3:18 PM
        And then fuel flow through the venturies!
         
        • Like Like x 1
        1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
          By continuing to use this site, you are consenting to our use of cookies.