1. Idle Mixture Screws?

    I am rebuilding the Carter BBD carb on my '79 CJ7, straight 6 258. Rebuild kit. Have it apart. The idle mixture screws (2) in the front lower part are both bent! Evidently the part of the screw outside the carb was bent. This does not allow the screws to go in all the way. My question... where to get my hands on two new idle mixture screws? Or other solution ideas. Thanks!!!!

  2. #2
    Join Date
    Dec 1999
    Virginia Beach VA

    Re: Idle Mixture Screws?

    I did a quick search and couldn't find a place to put replacement pins. I did find the whole carb on ebay for $140
    1975-79 JEEP 6CYL. ENG .CARB. 2barrel.CARTER.:eBay Motors (item 350240657818 end time Aug-22-09 20:50:45 PDT)

    however before I did that, I'd replace it with a holley or something else.

    Are those pins suppose to screw all the way in? I thought that they stuck out a bit, and if you cranked them all the way down they would bend? I'm probably wrong though, as it's been more than 10 years since I've seen one.
    My 2005 Wrangler Build Thread

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  3. #3

    Re: Idle Mixture Screws?

    I've seen that a lot on carbs. Don't know how or why but its just one of those things. Screw them in till they stop and look at the inside of the base, the needles shoulld stick out and be equal, if they are then don't worry about it. If not, try straightening them in a vice. Be carefull of the threads.

  4. #4

    Re: Idle Mixture Screws?

    Don't make them tighter than finger tight! Shouldn't even be that tight or they destroy the hole they fit into and idle will always be messed up.

  5. #5
    Join Date
    Nov 2005
    Albany~town, Oregon

    Re: Idle Mixture Screws?

    One thing about the Carter AFB BBD carbs, the mixture screws are not used in the conventional sense (ie they don't adjust the fuel) rather, these 'reverse idle' carbs, the 'mixture' screws opens or closes the auxiliary air bleed. This is why it's almost impossible to kill the motor with the screws all the way in. Regardless of the screw setting the motor will be supplied with sufficient idle fuel. <~Paraphrased from Dave Emanuel's book on Carter Carberators published back in '83
    Quick fixes are so named for how long they stay fixed.
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  6. #6

    Re: Idle Mixture Screws?

    search "Carter BBD fix" on google

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