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Q-jet experts.......need adjustment help

Discussion in 'The Garage' started by stallion85, Sep 8, 2004.

  1. stallion85

    stallion85 1/2 ton status

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    I just rebuilt a 4bbl Q jet I scored on a trade from a guy here in vegas. I rebuilt the carb and put a new float in it which was adjusted to the specs according to my model and year. The problem is now is she is running really rich. I tried adjusting the air fuel mixture screws but when I turned them in the idle went way up and did not lean it out. I started with them both 3 turns out from stop. Any tips on adjusting this bad boy? If the float was not adjusted properly would it cause this problem /forums/images/graemlins/dunno.gif Any tips on what to use besides needle nose pliers to turn the screws /forums/images/graemlins/grin.gif?
     
  2. k5mike

    k5mike Registered Member

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    you can get the proper tool to adj the q jet from advanced/autozone for around $20 I think.....if the float is off you are wasting your time at adj the mixture screws......I usualy start out at 1 1/2 full turns..that may be the same as your 3.....when you turn them in if the idle goes up adj. it down and go from there...you may need to rap on the engine a few times after adj to clear all the fuel out to check your adj.......it's bettter to be too rich than lean....lean likes to make new passage ways to the oil pan...like thru the top of a piston...good luck.
     
  3. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    [ QUOTE ]
    Any tips on what to use besides needle nose pliers to turn the screws

    [/ QUOTE ]

    Go to a "real" parts store and but the adjustment tool , worth it . I would suggest reading up on Quadrajets , the APT may need adjusted to run good in your engine combo , but I wouldn't just "play" with it without taking notes and remembering where you move it to .

    BTW just for kicks and grins , spray something around baseplate and throttle shafts and make sure it isn't sucking air in .

    Good for older Q-jets
    Great article on tuning
     
  4. lukebaby1

    lukebaby1 1/2 ton status

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    The proper way to adjust the mixture screws is to use a vacuum gauge attached to the manifold right behind the carb. It is better to buy two adjusting tools so you can put one on each screw. Assuming that you do not have any vacuum leaks the engine should stall out when you seat both screws all the way clockwise closed. If the engine does not stall then you need to check for vacuum leaks. Once you are sure than bring both screws back out a full turn counterclockwise, and start the engine. Once the engine is running look at your vaccum gauge and slowly turn the screws counterclockwise until you obtain the highest vacuum reading. I will also say that this is best done with everything in place including the air filter, as readings will fluctuate with componenets of the engine removed. Once you acheive the highest reading slightly turn the screws less than 1/16th back clockwise and you should be good to go! Hope this helps. /forums/images/graemlins/dunno.gif /forums/images/graemlins/dunno.gif /forums/images/graemlins/thinking.gif /forums/images/graemlins/peace.gif
     
  5. stallion85

    stallion85 1/2 ton status

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    Awesome thanks for the great info guys /forums/images/graemlins/woot.gif
     
  6. stallion85

    stallion85 1/2 ton status

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    Took the carb apart again and yes the float was not adjusted right /forums/images/graemlins/dunno.gif I adjusted appropriatley and now she is running smooth again. Before I pulled a plug and it was really black with carbon. After I fixed it the plugs were starting to tan out /forums/images/graemlins/thumb.gif I have still yet to test her out. maybe tonight /forums/images/graemlins/whistling.gif
     
  7. big pappa b

    big pappa b 3/4 ton status

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    I hate it when I'm right /forums/images/graemlins/peace.gif /forums/images/graemlins/peace.gif /forums/images/graemlins/peace.gif
     

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