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Correct original carb base gaskets for 67 GT 500

Discussion in '1965-1970 Shelby Mustang GT350 & GT500' started by Steve67, Apr 16, 2013.

  1. Steve67

    Steve67 Member

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    What should the original carburetor gaskets be for a 1967 GT 500 dual quad setup? Should there be any cutouts between the round venturi holes?

    I have multiple style gaskets to choose from. Some have a section cut out between both the two primaries and the two secondaries. I also have other gaskets with all four holes sealed completely from each other. These gaskets are about 0.100" thick.

    I understand that my original dual quad manifold is a dual plane 180 degee design. If I use the type gaskets with the cutouts between certain barrels (as explained above) I believe that I would be dampening the 180 degree effect.

    Any input or experience with performance differences between these type base gaskets would be greatly appreciated.

    Thanks in advance,

    Steve 67
     
  2. Bob Gaines

    Bob Gaines Well-Known Member

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    Four hole gasket paper thin from the factory.
     
  3. Steve67

    Steve67 Member

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    Thank you Bob, I thought so.

    Its been so long since I removed the originals that I really can't remember what was there. Percolation can sometimes result in warm conditions with these thin gaskets. I had this problem at times myself. A symptom of this is shutting the car down on a warm day and within a few minutes, fuel will start dripping from the throttle plate shafts onto the intake manifold. Another fix that can help this is lowering the float levels in the bowls. Some folks (including myself) have replaced these thin gaskets with more insulating thicker ones which can work well too.

    I still am unclear as to what these base gaskets with a cutout between each primary and secondary are all about (kind of kidney shaped). I had these installed and just yesterday changed to a 0.25" thick discrete full four hole gasket. We'll see how it goes.

    Its always good to know where we all started from.

    Thanks again for your expertise,

    Steve 67
     
  4. Bob Gaines

    Bob Gaines Well-Known Member

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    Many people change gaskets s well as other things from original in a attempt to help with percolation . Others have tried to issolate fuel log which is another souce of percolation.
     

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