Proper choke adjustment

Discussion in 'Troubleshooting & Diagnosis' started by 70RSZ28CAMARO, Jan 6, 2019.

  1. 70RSZ28CAMARO

    70RSZ28CAMARO Member

    35
    0
    Dec 19, 2003
    Long Island, NY
    Hey guys I have a 1970 Z 28 and I’m having problems with the choke the car has the old-style setup with a box n spring that sits on the manifold connected to a rod that controls the choke plate no matter what I do I can’t get the adjustment right I read that you pull the throttle back halfway and adjust from there I did that and the plate was closed but when I go to start the car the plate opens any help guys would be appreciated thanks
     
  2. Gary S

    Gary S Administrator Lifetime Gold Member

    21,531
    427
    Apr 14, 1999
    Bismarck, North Dakota
    I'm not familiar with Holley carbs. Does the Holley have a choke pulloff / vacuum break? If so, you simply adjust the choke rod so the choke closes fully but softly at 70 degrees air and engine temp and the engine off.
    That is the way it is done on Quadrajets and it works great. The vacuum break will open the choke slightly as soon as the engine starts, and that is needed to prevent flooding the engine. The vacuum break also needs to be adjusted to the factory spec which is different for each model and application. You can find those specs in a detailed carb book or on the instruction sheets that come with a carb kit.
     
  3. 70RSZ28CAMARO

    70RSZ28CAMARO Member

    35
    0
    Dec 19, 2003
    Long Island, NY
    Thanks Gary it does have a choke pulloff / vacuum break. One question when u adjust the choke rod does the throttle need to be partially open ? when it’s not the choke plate doesn’t move
     
  4. Gary S

    Gary S Administrator Lifetime Gold Member

    21,531
    427
    Apr 14, 1999
    Bismarck, North Dakota
    The choke plate needs to be free to move if any adjustments are to be made. If it is locked open by the throttle, release is however you need. On a quadrajet, slight movement of the throttle sets the choke so it closes. Once it is set, it moves freely with the throttle closed. A Holley might act different depending on how the mechanism is designed.
     
  5. 70RSZ28CAMARO

    70RSZ28CAMARO Member

    35
    0
    Dec 19, 2003
    Long Island, NY
    Hey Gary thanks for the Input i made some adjustments but are still having the problem Probably a difference between the Quadra jet n the holley

    Is anyone else familiar with the Holley stove choke adjustment procedure see above for background details

    Thanks lol
     
  6. COPO

    COPO Veteran Member Lifetime Gold Member

    16,784
    360
    Sep 15, 1999
    Ontario, Canada
    I got my original spring working better by removing the spring, then winding the coil up as tight as possible then install it. Make sure you have the correct spring. https://my1970z28.com/COPO/choke.htm
    I did no bending and it's been like this since I bought the car in 1981.

    [​IMG]
    Above and Below - This position is when the choke is closed.
    Note the choke rod L end on the bottom is up against the spring frame stop
    [​IMG]

    Below is when the spring pulls the choke rod down to fully open the choke flap from the heat off the intake.
    IMG_8251.JPG

    Below the choke is closed and works well in this position.
    IMG_8252.JPG

    Below is another view of the spring/rod with the choke closed.
    IMG_8253.JPG

    Below, Choke cover installed
    [​IMG]
     
    Last edited: Jan 11, 2019

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