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Thread: Spark Plug Gap

  1. 04-16-2019, 08:36 AM #1
    JPM
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    Spark Plug Gap



    Hi All,

    I had an MSD ignition installed recently and looking at the plug gap set by my mechanic it seemed rather large, like in the .055" range whereas the spec for NGK is .032". The MSD manual does not recommend a plug gap, they say, however judges the gap by compression and components which up to 10.5:1 is shown in the range of .050" - .060".
    I have run 1000 miles with this set up and have at times noticed a few misfires at high revs so I wonder if the gap has anything to do with it. I have reset the gap to .032" and will try this out.

    Are there thoughts on what the appropriate gap(if there is such a thing) should be?

    Regards,

    JP
    J P
    69 911T 2.4L w' 2.2S/E cams/Webers
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  2. 04-16-2019, 02:28 PM #2
    edmayo
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    Maybe your spark plug wires, I seem to remember that MSD recommends changing wires to the cotton thread -graphite variety. Not a fan of MSD.
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  3. 04-17-2019, 08:12 AM #3
    JPM
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    Yes, he did change the ignition wires. What I have seen in other posts is that a bigger gap produces higher energy release but cause pre-ignition and detonation risks in high compression engines.
    J P
    69 911T 2.4L w' 2.2S/E cams/Webers
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  4. 04-17-2019, 08:30 AM #4
    edmayo
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    Don't see that the gap could cause either condition
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