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Thread: vacuum leak

  1. #1
    Join Date
    Nov 2005
    Location
    paso robles Ca.
    Posts
    249

    Question vacuum leak

    a couple of weeks ago my motor developed a vacuum leak at the carb. (it is possible that this has been going on for a while since i have had some issues with problems of smooth running at lower rpm's at speed. ie: fifth gear 2200-2500 rpm. My neighbor who is a mechanic helped me diagnois the leak. I changed carb base gasket and throttle body gasket, no other changes or adjustments, now the motor will not run /idle below 2200 rpm. it will just die. on the first start after reinstalling carb when the motor died i got a big backfire out the carb. i don't want to buy another carb unless i have to, all gaskets appear to have been installed properly. any suggestions?
    on a less serious note, i replaced my 14" dia. air cleaner assembly with an oval cobra style cleaner from Ford, if i use the plastic spacer provided the hood won't close, without the spacer the base touches the top of float bowl screws and also the back side of the cover has to be wedged under cowl. any input would be appreciated.

  2. #2
    Join Date
    Nov 2005
    Location
    paso robles Ca.
    Posts
    249
    oops, accidentally posted twice, so i should get twice as much advice

  3. #3
    Join Date
    Sep 2004
    Location
    Bainbridge Island, WA, USA.
    Posts
    196
    Scott,

    I can't help you with your carb problem, but I did have a similar problem regarding hood clearance with my oval air cleaner. I solved the problem by cutting the plastic spacer at an angle. I ended up with the end of the spacer facing the windshield approximately 1/8" lower than the side facing the radiator. Hope this helps.

    Bob

  4. #4
    Join Date
    Nov 2003
    Location
    Cincy, OH, USA.
    Posts
    376
    timing issues come to mind or a blown power valve in the carb. What say y"all.
    Scott
    4279454
    SA 428
    3:54

  5. #5
    Join Date
    May 2005
    Location
    Roseville, Ca., USA.
    Posts
    523
    If your carb was previously adjusted to compensate for the vacumn leak, it would now be way to rich now. What kind of carb are you running?
    Last edited by RJacobsen; September 24th, 2007 at 09:47 PM.
    Rod
    Roseville, Ca.
    289 FIA #9152 "The Flintstone Cobra"

  6. #6
    Join Date
    Jan 2003
    Location
    Harrisburg, PA, USA.
    Posts
    657
    Scott,
    Are you running a tall intake. I had a similar problem with my second car with was resolved by having a small amount machined off the carb mounting surfaces. The intake was a dual quad high rise on a 289 sb.

    -Geary

  7. #7
    Join Date
    Nov 2005
    Location
    paso robles Ca.
    Posts
    249
    i discovered that the gasket was the wrong one, it was blocking the idle ports, waiting for a new gasket.
    can i use the air cleaner base without the spacer, i was thinking i could dimple the base where it touches the carb, i do have a tall intake, what would change if i had it milled down.

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