Avs secondary tuning ?

Fuel and Air Systems

  1. mbaird

    mbaird mbaird FABO Gold Member

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    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 Utube channel 318willrun

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    • 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
     
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    • yellow rose

      yellow rose Doctor of Thinkology.

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      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.
       
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      • 1969383S

        1969383S FABO Gold Member FABO Gold Member

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        And then fuel flow through the venturies!
         
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