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Thread: chevy inline six - need help

  1. #1
    Road Devil's Member Brian_RDeurope's Avatar
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    chevy inline six - need help






    Engine: 250 inline six
    new valve springs and seals installed; compression just fine
    intake: aussiespeed manifold w 4brl pattern
    carb: 390 2brl Holley (AN4160) with adapter bolded to the intake; bigger jets
    carb fload ok
    vacuum line is proof; vacuum line connect to ported vac not to full manifold port
    header: split headman headers
    ignition: stock distributor with petronix modul + coil
    timing: 4 dgr before bdtc
    stock cam
    plugs: chevy correct ac delco
    exhaust: 2.5“ behind each header + Trush glasspack length pro pipe


    sympthoms:

    plug 2 + 5 + 6 are black the rest is white

    no ploblems while running on idle or without load

    with load: bad accelaration, missfiring with higher rpmīs

    I dont know what else to do with it; any idea how to get everything to work together ?
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  2. #2
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  3. #3
    Road Devil's Member rabbit's Avatar
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    Do you have a full 12-14.4 volts to the coil when the engine is running?
    What kind of vacume do you have at idle?

  4. #4
    Road Devil's Member
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    chevy inline six - need help

    Go to the local engine shop and ask for a V-8, I am sure it'll fix the problem.


    Sounds like timing, or detonation. I'd check what the advance does when you run the RPMs up, and maybe give a shot of some cleaner through the valves... Also is compression okay on all the cylinders?



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    Last edited by John C; 08-12-2016 at 02:00 AM.

  5. #5
    Road Devil's Member Jailbird's Avatar
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    The timing seems slow to me only 4°? I have a brand new HE I distributor for inline Chevy if you decide to change it over. Misfiring tru exhaust? Or backfire tru the carb?
    Jeremy Wilks
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    Texas Chapter

  6. #6
    Road Devil's Member Madness's Avatar
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    I still think its timing related... and that you should try hooking the advance to full-time manifold vacuum, instead of that timed port.
    Josh Lowrey
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    "Faster, faster, faster, until the thrill of speed overcomes the fear of death"

  7. #7
    President Patrick's Avatar
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    i agree sounds like something in the timing, could the petronix be breaking down or are you using a resistor before your distributor? week vacuum not allowing the advance to work or even a cracked cap

  8. #8
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    Did you get this problem straightened out? Looks like your adapter is adjustable. Slide it back toward the 5-6 cylinders. See if that helps with the leaned out plugs.

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