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Customs 235 had misfire while crusing.... Help..

Discussion in 'The Hokey Ass Message Board' started by 51fordor, Apr 16, 2014.

  1. 51fordor
    Joined: Sep 16, 2010
    Posts: 215

    51fordor
    Member

    So I have a 54 chevy with a 57 235 in it. The car had a HEI distributor installed by the previous owner. Other than that it appers stock. The car ran amazing when I first purchased it, but slowly started to have issues with the carb. The carb was clogged up horribly, and the plunger was shot. I rebuilt the carb and the car did now start much easier, and run better when being put under a load.

    When I am just crusing at any given speed like say 45, the car has a hiccup you can hear and feel. It's very mild but still enough to drive me freakin nutz. It becomes more noticeable once the car is fully up to temp. I went ahead and changed the plugs and wires thinking they might be the issue but that made zero difference. Could the misfire/hiccup when crusing be a float adjustment issue?
    Thanks in advance for any input guys!
     
  2. bobwop
    Joined: Jan 13, 2008
    Posts: 6,099

    bobwop
    ALLIANCE MEMBER

    are all vacuum hoses hooked up and not leaking?
     
  3. 51fordor
    Joined: Sep 16, 2010
    Posts: 215

    51fordor
    Member

    No leaks. Checked intake/exhaust manifolds and vaccum advance. Thats why i was thinking float adjustment.

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  4. My wag is that you have a "dirty" gas tank. Is there a filter between the tank and carb? If so , change it. If not , you need one.

    Ben
     

  5. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,856

    Mike51Merc
    Member

    Could be a mechanical issue like a sticking valve.
     
  6. 51fordor
    Joined: Sep 16, 2010
    Posts: 215

    51fordor
    Member

    New tank last year and new lines. Just put a new glass filter on it when I did the rebuild. I am starting to think if it's not carb related that it might be in the distributor.

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  7. VoodooTwin
    Joined: Jul 13, 2011
    Posts: 3,455

    VoodooTwin
    Member
    from Noo Yawk

    I'm thinking ignition related. Check the easy stuff first. Solid ground connection? Loose wire at the ignition switch? Etc.
     
  8. Fogger
    Joined: Aug 18, 2007
    Posts: 1,559

    Fogger
    Member

    Best advice is to first check the fuel filter and if it's clogged up install one before the fuel pump and another between the pump and carb. Your carb being clogged up was a sure sign of a dirty fuel system. If that's the issue time to remove the tank and either replace or have it cleaned out. Been through the same problem with my '55 Chevy.
     
  9. 54fierro
    Joined: Jul 6, 2006
    Posts: 493

    54fierro
    Member
    from san diego

    I've had that problem a couple of times, first time I pinched a wire between the cap and distributer till it was grounding, second time was a bad condenser.

    what's the saying "80% of carburetor problems are ignition" :)
    good luck, start with the easy stuff first like they said
     
  10. 51fordor
    Joined: Sep 16, 2010
    Posts: 215

    51fordor
    Member

    Like i said the tank is brand new as are the lines and filter. I opened the carb up last night and it was clean inside.

    One thing I didn't mention is that the hiccups don't start till the car gets up to a good operating temp. When engine is cold there are zero issues.

    All the wiring is sound. The hei distributor is an old delco remy unit. Might just replace it.

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  11. inline 292
    Joined: Aug 25, 2006
    Posts: 296

    inline 292
    Member

    Try going up one size on the carb main jet. Thats pretty easy & if nothing else, it'll eliminate it being a lean condition.
     
  12. Thumper
    Joined: Mar 7, 2005
    Posts: 1,610

    Thumper
    Member

    Once it warms up maybe a plug wire is breaking down or maybe even the coil. It sounds heat related to the ignition. Just my guess....
     
  13. You haven't made much mention of what your tune-up is. Do you know what your initial and total timing is? Are the mechanical and vacuum advances working properly in your HEI? If you have an automatic choke is it adjusted properly and fully open when the engine is at operating temperature? Do you have good, steady manifold vacuum at idle and cruising speeds?
     
  14. Ulu
    Joined: Feb 26, 2014
    Posts: 1,767

    Ulu
    Member
    from CenCal

    This sounds sorta like a low float/dirty fuel system.

    Particularly since it changes with temperature. Still a bad coil can do that too, but your coil is fairly new right?

    Anyhow, If a car runs better or worse when cold/hot, I first look to the mixture. Cold engines want more gas, hot ones want less. So to diagnose this I'd first fatten up the idle mix a lot then go cruise steady at 45 in it. If the problem gets better good, if not lean it way out & try again. If there's a response, it's likely fuel system related.

    If nothing really improves either way, look to ignition.
     

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