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Losing vacuum

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  • Steve G.
    Expired
    • November 24, 2014
    • 411
    #16
    Re: Losing vacuum

    Originally posted by Kenneth Files (13799)
    Jim, I have a hydraulic lifter engine with the single point setup.
    Steve, I did not pump the throttle. I will try this.
    This engine has about 1K miles since rebuild. The 2 things done to improve performance was to eliminate heat to the heat slot. This really helped, but it still had a miss in town going into 4th gear going up a hill. This miss was eliminated by raising the fuel level in the bowls with a .245 float level. The previous level was the spec in the ST-12 of 5/16." The .245 was recommended by a fuel systems vendor who advertises in the Driveline.

    Thank you for the input..
    Ken
    Raising the fuel level in the bowl (reducing the distance from float to cover) richens the mixture. Holding the heat riser open lowers the air temp and raises it's density which requires more fuel for the volume of air it's taking in. Factory specs are no longer applicable. Denser air, more fuel needed. Makes perfect sense. You may still not be rich enough.

    Steve
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      • Mike E.
        Extremely Frequent Poster
        • February 28, 1975
        • 5134
        #17
        Re: Losing vacuum

        62 250 and 300hp have single points from the factory, 340 and 360 are dual points. Good to check and see what's in there now.
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          • Jim L.
            Extremely Frequent Poster
            • September 30, 1979
            • 1805
            #18
            Re: Losing vacuum

            Originally posted by Mike Ernst (211)
            62 250 and 300hp have single points from the factory, 340 and 360 are dual points. Good to check and see what's in there now.
            I didn't know that, but I got it now. Thanks Mike and Ken.
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              • Frank D.
                Expired
                • December 27, 2007
                • 2703
                #19
                Re: Losing vacuum

                Yes - single points from factory....

                Your fuel sounds adequate but if that incline is causing a float to stick in the bowl that's bad news. Might want to pop the top of the carb off and check that floats are centered and operate smoothly.

                Maybe time to check out the ignition. I've seen some crazy stuff. Including having plug wires crossed and the car acts relatively fine until under load. I've also seen arcing from bad wires in high load conditions. Carbon tracking in the distributor cap can cause grief as well....
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                  • Kenneth F.
                    Very Frequent User
                    • September 30, 1988
                    • 282
                    #20
                    Re: Losing vacuum

                    Frank, I will check both of your suggestions. I have another set of wires and a cap.

                    Thank you,

                    Ken
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