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Need some advice in South Louisiana

Discussion in 'The Hokey Ass Message Board' started by Sutton, Oct 7, 2005.

  1. Sutton
    Joined: Apr 7, 2005
    Posts: 699

    Sutton
    Member
    from BTR

    Hey guys-

    I am have been having a problem with my car that I cannot seem to fix. The motor is a 350 chevy, mild cam, 650 holley. In march my father and I updated the distributor to a HEI , new coil, wires and had the carberator rebuilt. The timing seems to be right when I put a light on it (around 7 degrees advance) but the vaccum off of the manifold is low.

    The car runs fine, but when I drive at high rpm for 10 or more minutes, the car starts to want to backfire. It runs like shit until it has had time to cool down for at least an hour. I have looked for wires close to the engine, but everything seems to be ok. We also added a ron francis hot start kit, which could be the culprit. My dad also said it may be vapor lock, but the tank is vented. Has anyone else had this problem, or know of anyone in this part of the state that could look at it with me, since my tools and knowledge (father lives in north LS) are fairly limited.

    Thanks in advance.
     
  2. HemiRambler
    Joined: Aug 26, 2005
    Posts: 4,208

    HemiRambler
    Member

    Low vacuum suggests (amoung other things) that the TIMING is OFF. Double check it starting from TDC just to be sure. Also is the Mechancial and Vacuum advance working?? Double check to be sure.

    Lastly check the spark (bright blue)- a WEAK spark can cause a mis (backfire) under the right circumstances, but allow it to start fine.

    And of course WHAT do the PLUGS look like??? Are they suggesting carb/mixture problems - you said you "had" it rebuilt - never trust anyone's work - double check everything - even your own!!!

    Holley - check the fuel level in the bowls - adjust if necessary - running it TOO high can cause it to pull 'extra' fuel under cruise conditions - resulting in miss/backfires. Fuel pressure - check to be certain (6, 6-1/2 psi max - a little less won't hurt)

    Start it and run it at part throttle - secondaries should be CLOSED and the primary should NOT be dumping fuel. A bad float setting, excess pressure, etc will often sound like a intermittent miss especially at part throttle when you get a little air moving - you can watch it dump out of the boosters sometimes. Wear safety glasses when starign down your carb - inches away from a backfire in the face could play havoc with your future ability to see!!!

    vapor lock - pull the sight plug while idling - vapor lock is ultimately a LACK of fuel so you will see it there - or rather NOT see it!!! Do you have a clear fuel filter - is it FULL while running - if so NOT vapor lock.

    SPARK(timing and intensity)......FUEL(mixture and leaks/flooding).......

    check the power valves is it' backfired through the carb -also don't over look the needle and seats - even though it's been rebuilt - soemtimes a careless rebuild dislodges particles that can impeed the function of the needle and seat - stuck OPEN or CLOSED.

    Just thinking out loud.............


     
  3. BenD
    Joined: Mar 5, 2001
    Posts: 1,591

    BenD
    Alliance Member

    If all that doesn't work, try Simpson's Automotive in Baton Rouge. On Florida Blvd., downtown near the tracks.

    Ask for Jay DeLozier (my brother) and tell him you're from the Hamb.
     

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