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600 holley

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  • 600 holley

    Hello everybody. I,m messing around with a holley 600 cfm out of the box and when I turn the mixture screws all the way in the car keeps runnin. If i turn them out it runs worse! Does any body think this is a bad carb? I thought it should stall closing them. That's the way it used to be. Any suggestion would be great. Thanks..........Bill

  • #2
    It should stall, or at least run really rough, when the mixture screws are turned in all the way. Sounds like it's not right.
    1960 Hard Top/430
    Thunderbird Registry Number 1231


    • #3
      Thanks. This thing is from summit. I think I'm headed to edelbrock. I have one on my 66 tbird and it runs like new.


      • #4
        I agree with you, try out a new Edelbrock. Even if you figured that Holley out, you would tinkering with it every time the weather changed!! LOL!!
        The 1960 Ford Thunderbird. The WORLD'S most wanted car....

        VTCI Member#6287.


        • #5
          It sounds like something simple - is your float level right? - are your float-bowls snugged up?

          It all points to fuel getting in where it shouldn't.

          I had this problem once with a slowly sinking brass float which ever so gradually riased the fuel level and I got you symptoms, also on a 600 'somebody' had left the primary float-bowl screws fairly loose, had the same symptom you have described,merely snugging them up fixed the problem

          I have used Holleys for years and apart from snafus like above I have had no problems with them - the 780 one on my hot-rod '55 F100 was new when I bought it in '78, it still runs sweet and that float problem has been the only one I've had.
          A Thunderbirder from the Land of the Long White Cloud.


          • #6
            I'll try that first before kicking out another $300 and change.


            • #7
              Originally posted by tbirds8 View Post
              I'll try that first before kicking out another $300 and change.
              I would try it, I am running a small 600 or 625 holly on my olds 455 and the motor loves that carb. That is after I tried a 1411 and had problems with overload in the turns, then a road demon that was true to it's name "demon" that carb never worked right.

              Friend built this old holly and my car woke up and runs better than it has since I first started on it.