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Thread: Black spots on driveway
          
   
   

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  1. #1
    Johnwalkeasy is offline CHR Member Visit my Photo Gallery
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    Jul 2005
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    Rex
    Car Year, Make, Model: 68 chellve and 67 chevy pick up
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    103

    Black spots on driveway

     



    68 Chevy, 327, 4 barllell. When truck cranks it puts two big black spots on driveway, just under tail pipes. This is ofcourse carbon. What could be causeing this? Thanks, John.
    John

  2. #2
    mopar34's Avatar
    mopar34 is offline CHR Member Visit my Photo Gallery
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    Feb 2006
    Location
    Stewartstown
    Car Year, Make, Model: 34 Ply PE sdn; 57 Olds 88 J2
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    1,953

    Common floor coating behind a 371 Olds with J2 power. I just move the cars around to keep the coating uniform.

  3. #3
    thesals's Avatar
    thesals is offline CHR Member Visit my Photo Gallery
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    Feb 2004
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    san diego
    Car Year, Make, Model: 66 mustangFB, 69 econline Drag Van
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    thats only a problem if shes doing that after shes warm...... when its cold it should run rich thats what the chokes job is, to choke it of air, once engine is up to temp it should pull off the choke and not be running rich anymore.... if it still does it... then you might need to adjust your idle mixture a little bit
    just because your car is faster, doesn't mean i cant outdrive you... give me a curvy mountain road and i'll beat you any day

  4. #4
    mopar34's Avatar
    mopar34 is offline CHR Member Visit my Photo Gallery
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    Car Year, Make, Model: 34 Ply PE sdn; 57 Olds 88 J2
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    Only on start up with a dead cold engine. Nothing spitting or smoking after warm up. Still a little rich, but haven't had time to adjust. Been sitting since November, but will be re-activated soon.

  5. #5
    thesals's Avatar
    thesals is offline CHR Member Visit my Photo Gallery
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    san diego
    Car Year, Make, Model: 66 mustangFB, 69 econline Drag Van
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    alright try leaning out your idle mixtures a little bit and see if that cures it some.....
    just because your car is faster, doesn't mean i cant outdrive you... give me a curvy mountain road and i'll beat you any day

  6. #6
    Twitch's Avatar
    Twitch is offline CHR Member Visit my Photo Gallery
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    Mar 2005
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    L.A.
    Car Year, Make, Model: 73 Z-28
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    My straight 8 was doing that on my old carb that someone had set up to use a manual choke instead of auto. A new rebuilt with an auto choke helped but not at first till I got the choke setting dialed in right which gave enough richness to run but not puke carbon. Had to back off the original idle flow settings to more lean too.
    There is no substitute for cubic inches

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