Carb synchro

Discussion in 'Mechanics Garage' started by shirmik, Sep 11, 2018.

  1. shirmik

    shirmik New Member

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    Hi all,
    Anyone have any tips on the best way to sync the carbs on a 1986 Interceptor?
    I have rebuilt all four of them, new jets, o rings, set the floats etc. Tried with the 4 vacuum gauge setup but didn’t have a lot of luck. One of the right side cylinders is popping when revs are held at about 4000rpm and no matter what adjustments I make, won’t fix it.
    Would be really nice for some advice before I gas myself in the shed with carbon monoxide, lol.....

    Any help greatly appreciated.
     
  2. squirrelman

    squirrelman Member

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    popping means too lean in most cases or bad spark.

    could be failed diaphragm installation, which would be apparent when revvvvving......... if a slide doesn't lift. otherwise, a too-small idle jet or fuel blockage somewhere, possibly a synch error or not.

    find which cylinder pops, then switch ignition coils to test. compare that plug to others, switch plugs around.

    best way for inital synch is with eye-reference to the throttle plate edge where it first begins to expose the first progression hole to sight.

    @4k you're in a transition phase from top of idle jet to needle position with an overlap of both.
     
    Last edited: Sep 12, 2018
  3. shirmik

    shirmik New Member

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    Thanks for that, will have a look and see what I can find out. In the process of re setting the valve clearances at the moment. Cylinder 1 and 3 were a bit tight. Might have had a valve not closing completely on 3 prior to firing. Can’t hurt to reset them though.
    Thanks squirrel man.
     

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