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Thread: 950 Dominator/Gen 3/No Transition Slot Visible

  1. #1

    Default 950 Dominator/Gen 3/No Transition Slot Visible

    Hi all. I bought a brand new Holley Gen 3/950 Dominator in hard core grey. When I set the idle to around 1100 RPM, I found out that no transition slot is visible. The idle bypass valve is fully closed. When I took of the carb to check the butterfly position, I found out that it needs four complete turns of the idle speed screw, to make even a bit of the transition slot visible. In this position (just on the primary side) my engine idles at 2000+ rpm.

    Does anybody have same experiences with that carburetor, or an idea what could be wrong with this carb? Are maybe the butterflies installed from the wrong side? Or a wrong base plate?
    I have attached two pics from the butterfly position. Thank you very much in advance. With best regards, Jan.

    (First pictures is with one turn in of the idle speed screw, and the second with four turns in.)

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    Click image for larger version. 

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  2. #2


    Hello. I did some looking around and decided to go look at the instructions for your carburetor. Don't take this as me being a smart azz, but I was kinda curious why it would take so many turn to get to the transition slot. The instructions didn't state where the below relation was, but mentions this:

    Your new Holley Aluminum Ultra DOMINATOR carburetor has been setup from the factory with optimized throttle plate positioning in
    relation to the transfer slots. If after installing the carburetor, you find the idle speed needs adjusting, it is recommended to adjust the
    idle speed utilizing the new Idle Bypass Valve. If the proper idle speed cannot be achieved using the Idle Bypass Valve, the curb idle
    screw(s) can then be adjusted.

    So if you have to, call Holley Tech line to find out where they set the throttle plates in relation to the transfer slots, and then use the idle bypass screw where the air filter stud is normally at to adjust your idle speed from there. Hope this helps you some. Sean

  3. #3


    Hi Sean, and thank you for your fast reply.

    I read the same instructions in the manual which came with the carb, but this doesn't really help to adjust the idle speed screw correct. In my opinion, the Dominator should work the same like all other Holleys which have a transfer slot. But four turns can't be correct. I already sent Holley tech line an email, but no answer so far. Later on I will try to call them. Thanks again. Jan

  4. #4


    I think what they're trying to tell you is to "not adjust the idle speed screw from factory setting". If you need idle speed adjustment, use the bypass screw first. If you find in your setup that the idle bypass screw does not give you enough adjustment, then use the "normal" idle speed screw to fine tune from there. With this being a RACE style carburetor, it's not going to setup like a typical street carburetor. Or let me rephrase that to say, it's not meant to be configured like a typical street carb.

    I personally think the reason the transfer slots are so high up in the bores, is because in typical drag race, there's a launch RPM which would have you holding the throttle X amount open before going WOT. I wouldn't bet my life on that, but that would be my thinking on it.

    Thanks, Sean

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