Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

QJet Choke and Fast Idle Questions

Discussion in 'The Garage' started by Rolled, Sep 13, 2006.

  1. Rolled

    Rolled 1/2 ton status

    Joined:
    Jun 16, 2002
    Posts:
    683
    Likes Received:
    0
    Location:
    Anchorage, Alaska
    Having some issues with a rebuilt quadrajet I purchased from Holey.

    Backround -

    82 K20
    M code heavy emission
    hot air choke
    350
    465
    everything is hooked up correctly and nothing is missing under the hood. I just put a crate motor in and made sure everything was installed back to stock so I can pass emissions.


    Here is the problem I am having -

    The choke just does not seem to opperate correctly. It always wants to go to fast idle even if the motor is at opperating temperature. If I play with the throttle I can get the fast idle cam to fall into the correct position but it just does not want to stay there.

    It looks as though gravity is suppose to drop the fast idle cam when the choke coil expands but the linkage is pretty ballanced so there is nothing forcing it down...

    I am assuming the spring tension of the choke coil is suppose to force the choke closed when cold. That is how I have it set up. That works just fine but when it heats up, nothing is forcing it open. The coil just backs off and gravity is suppose to make it open?????


    If I am wrong and the coil is suppose to force it open when hot (which I prefer) then there is nothing to close it when cold. nothing at all since the fast idle cam and butterfly valve would have to fight gravity all on their own to close up???? So I doubt that is correct...

    Either way, how the hell is this hot air choke and fast idle cam suppose to work and how does one set it up?

    I have a book and the carb came with manuals and I even have directions from a rebuild kit but none of them reall explain how this thing works. If I set it up like I think the books tell me to, there is nothing to controll the opening of the choke other than gravity so I must be doing something wrong :(


    Tips, advise, tech article, hand holding :), any help will be appreciated.
     
  2. makovai

    makovai 1/2 ton status

    Joined:
    Jun 6, 2006
    Posts:
    854
    Likes Received:
    0
    Location:
    oregon city
    i have 1 word for you Edelbrock.
    I bought 4 holley 600s and had a holley gooroo come over and he rebuilt 3 of them and none would stay tuned for more than a day. I had this guy bout ready to commit suicide over these carbs.
    I bought a brand new 1406 edelbrock and adjusted the idle and haven't touched it for 3 months now.


    Note: i din't really want 4 of them, its just when the original was acting up i ran an ad for a replacement and i started trading goodies for them and somehow ended up with 4.
     
  3. Rolled

    Rolled 1/2 ton status

    Joined:
    Jun 16, 2002
    Posts:
    683
    Likes Received:
    0
    Location:
    Anchorage, Alaska
    I wish I could use an aftermarket. But I can't. I have to pass emissions and I must have original equiptment on this rig. if not for that, I wold swap it to TBI.

    The carb was a Holley reman but it is a Rochester Quadrajet...
     
  4. pauly383

    pauly383 Daddy383 Staff Member Moderator

    Joined:
    Jul 22, 2001
    Posts:
    16,217
    Likes Received:
    1
    Location:
    Mesa , Arizona USA
    You adjust the choke coil so the flap door over the primaries is open a little ( your tune up specs in your manual ) . The weight thingy will drop when choke heats up AND you blip the throttle to release it ( remember you blip throttle once upon entering truck to set the choke ) .
     
  5. bigblock72

    bigblock72 1/2 ton status Premium Member GMOTM Winner

    Joined:
    Oct 18, 2005
    Posts:
    1,235
    Likes Received:
    59
    Location:
    American Fork, Utah
    Is your choke spring on the intake with a rod or is it a round housing on the side of the carb?. If I know what style of choke you have I can get you pointed in the right direction.
     
  6. Rolled

    Rolled 1/2 ton status

    Joined:
    Jun 16, 2002
    Posts:
    683
    Likes Received:
    0
    Location:
    Anchorage, Alaska
    Thats the way it looks but it fails to fall when heated. If I agressively fook with the throttle several times it will slowly work its way down... The weight moves freely with no binding at all. it just does not want to go down. Sometimes when driving, it manages to up a bit from bumps in the road...

    It, quite often, goes to the second step on the cam. It is set at 700 rpm and 1900 rpm fast idle. And I believe there is a second step on the fast idle cam that runs at 1450rpm. The motor really likes hanging out there...


    I took out the fast idle screw and forced the choke wide open. It runs good but don't know what it will be like on cold mornings. I also have an appointment with the emission inspector today. I hope they do not notice the fast idle screw and choke... I was certain the Jiffy Lube emision inspector would not notice but they failed me for having a new motor. New motors here have to be inspected by a special station. I hope these fellas do not notice what I did to the choke...



    Is there any way to adjust the weight so it falls and stays down? I noticed a lot of linkage around it. Maybe some of that controlls the weight...
     
  7. bigblock72

    bigblock72 1/2 ton status Premium Member GMOTM Winner

    Joined:
    Oct 18, 2005
    Posts:
    1,235
    Likes Received:
    59
    Location:
    American Fork, Utah
    The bi-metal spring controls the position of the fast idle cam and the choke butterfly as well. Your problem is related to the choke bi-metal spring not getting hot enough to open the choke all the way and drop the fast idle cam down. If you can describe what style of choke you have I can help you fix it correctly.
     
  8. pauly383

    pauly383 Daddy383 Staff Member Moderator

    Joined:
    Jul 22, 2001
    Posts:
    16,217
    Likes Received:
    1
    Location:
    Mesa , Arizona USA
    try to lube the linkage , you may have overtightened the carb too , putting pressure on it .
     
  9. Rolled

    Rolled 1/2 ton status

    Joined:
    Jun 16, 2002
    Posts:
    683
    Likes Received:
    0
    Location:
    Anchorage, Alaska

    pauly - I'll look into overtightening and try lubing it up.


    Thanks for the help guys. Hopefully I'll get this solved and put it behind me... I'm about ready to buy a 1973/1974 Ksomething and swap out the drive train. there is no visual inspections for rigs older than 1975. This way I can do whatever i want under the hood and scrap a carb all together :)
     
  10. bigblock72

    bigblock72 1/2 ton status Premium Member GMOTM Winner

    Joined:
    Oct 18, 2005
    Posts:
    1,235
    Likes Received:
    59
    Location:
    American Fork, Utah
    If it has tubes going into the manifold then the choke spring is in the housing on the side of the carb. The exhaust crossover may be restricted down to a point where the choke spring isn't getting hot enough to open fully. Try getting an electric choke for it and your problem should be solved. It's an easy swap, just remove or drill fasteners from choke cover (should be three screws or rivets) and replace with an electric one. They are around $40.00, and try getting one for a 85-86 car or truck with a 350, it will bolt on once you cut the little alignment nubby off. Between the exhaust heat and the electric heater your choke should work good.
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,979
    Likes Received:
    189
    Location:
    Roy WA
    Don't forget, if the choke linkage isn't "long" enough, you'll end up tightening the coil to the point that it won't expand far enough to disengage the idle cam. Buddy could never get his right either (One of the Edelbrock Q-jets though) it was either choke on all the time, or off all the time. I'm sure now that it was the length of the choke rod.
     
  12. Rolled

    Rolled 1/2 ton status

    Joined:
    Jun 16, 2002
    Posts:
    683
    Likes Received:
    0
    Location:
    Anchorage, Alaska
    I tore it apart, soldered a small nut on the weight, lubed everything up.

    It is working correctly now :)

    I think the real problem was either the bolt holding the choke housing on or the screw to the linkage in thechoke housing being to tight.

    If I overtightened either of those, the linkage would bind. I have a feeling one of them was just a hair to tight and kept the weight from its freefall.
     

Share This Page