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Pulsating Throttle on 56 WCFB

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  • Mark P.
    Very Frequent User
    • July 31, 2003
    • 407

    Pulsating Throttle on 56 WCFB

    Just started my 56 dual quad for the first time since a total engine and carb rebuild and the metering rods on the primary carburetor are pulsing up and down and the engine revs at 2 second intervals rather than iding smoothly. Is that a jet placement issue or a power valve spring issue? Any thoughts would be appreciated!

    Thanks,
    Mark
    Mark Pugmire
    54 Pennant Blue
    56 Cascade Green Dual Quad
    56 Arctic Blue Dual Quad
    66 Nassau Blue 427 L36 Convertible
    67 Marlboro Maroon L79 Coupe
  • Clem Z.
    Expired
    • January 1, 2006
    • 9427

    #2
    Re: Pulsating Throttle on 56 WCFB

    Originally posted by Mark Pugmire (40391)
    Just started my 56 dual quad for the first time since a total engine and carb rebuild and the metering rods on the primary carburetor are pulsing up and down and the engine revs at 2 second intervals rather than iding smoothly. Is that a jet placement issue or a power valve spring issue? Any thoughts would be appreciated!

    Thanks,
    Mark
    try it without a power piston spring and see if that fixes the idle problem. if it does then find a spring that stops the pulsing by allowing the piston to stay down at idle

    Comment

    • Mark P.
      Very Frequent User
      • July 31, 2003
      • 407

      #3
      Re: Pulsating Throttle on 56 WCFB

      Thanks for the response, Clem. So is the spring potentially too weak? Is that what's allowing it to drop?
      Mark Pugmire
      54 Pennant Blue
      56 Cascade Green Dual Quad
      56 Arctic Blue Dual Quad
      66 Nassau Blue 427 L36 Convertible
      67 Marlboro Maroon L79 Coupe

      Comment

      • Clem Z.
        Expired
        • January 1, 2006
        • 9427

        #4
        Re: Pulsating Throttle on 56 WCFB

        Originally posted by Mark Pugmire (40391)
        Thanks for the response, Clem. So is the spring potentially too weak? Is that what's allowing it to drop?
        at idle the vacuum should over come the spring tension and keep the power piston at the bottom of the chamber so the metering rods have the larger diameter in the jets,lean stop. you either have not enought vacuum at idle or too strong a spring. check your timing and valve lash as this effects the vacuum at idle

        Comment

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