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Thread: Tune advice

  1. #1
    Senior Member black 94's Avatar
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    Tune advice

    Helping a buddy get his truck lined out so we can take it to grudgement day. The truck is a 388 sbc single 88mm vs turbo big fmic blow thru carb deal with the msd programable 6 box. My question is I got the afr at a steady 10.7 on the wideband and pulling the timing down to 20 degrees at 10# but the truck is breaking up on a pull any ideas? I know it's still a little rich but didn't think that's so bad to cause it to break up. Has 3924 plugs gapped at .020

  2. #2
    Banned George C's Avatar
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    Not enough timing too much fuel

    Carb shoot for 11.6
    And 20* id go 25 honestly at such low psi

  3. #3
    Senior Member black 94's Avatar
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    Ok thanks George. We were leaning it down a little at a time figured we were still way rich but we're working on that. But I wasn't sure how much more timing would be safe. Thanks again for the reply if this rain goes away by tonite we will put some more timing in it and take out some more jet and see how it goes.

  4. #4
    it's soo-tack sutyak's Avatar
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    Also possible the plugs are too hot, even though they're gapped tightly. A quick google search shows the 3924 plugs aren't great for FI applications.
    http://www.autolite.nl/bougies/pdf/pdf-heatrange.pdf
    mark
    '04 Mach 1. Built. Turbo. 667whp/631wtq
    '06 Focus. Built. Turbo. WMI. 12.43 @ 115 (sold)
    '03 Mach 1 : 12.61 @ 106.59 (sold)
    he's into that, that spiritual stuff. <><

  5. #5
    Banned George C's Avatar
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    Typically a sbc takes 36 ish timing so 10 psi will be 24 25 * on 93
    Hot plug is fine if compression is low and timing is low... But without knowing the reference for sbc i cant say if current plug is hot or not....but the plug will tell you

  6. #6
    Senior Member black 94's Avatar
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    I don't know the details on the internals. If I would be better off going with a 23 or 22 plug we can there getting changed out b4 the track anyways. Thanks again fellas we didn't get to it tonite hope to clean the tune up soon tho.

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