308 GTB MSD units and plug gap | FerrariChat
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308 GTB MSD units and plug gap

Discussion in '308/328' started by johnvwatts, Aug 9, 2008.

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  1. johnvwatts

    johnvwatts Formula Junior

    Jul 7, 2007
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    John v watts
    #1 johnvwatts, Aug 9, 2008
    Has anybody researched the best plug gap for a 308 GTB running with twin MSD's? The car has a single distributor but with twin magnetic pickups. Tried stock .025" but found .045" much better. MSD recommend .05" to .06" which seems very big.
     
  2. luckydynes

    luckydynes F1 Rookie

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    #2 luckydynes, Aug 9, 2008
    When I run big gaps like that with my MSD DIS4 the center electrode deterioates really fast and crooked . .. . I'm all the way back down to .03 and will start working back up again. I'm pretty sure MSD told me to keep the stock plug gap +.01 but the DIS4 is capacitive discharge so not sure if that makes a difference . .. are your MSD's capacitive discharge or just multiple spark units?
     
  3. snj5

    snj5 F1 World Champ

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    #3 snj5, Aug 9, 2008
    I'm running about .38
     
  4. thecarreaper

    thecarreaper F1 World Champ
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    #4 thecarreaper, Aug 9, 2008
    i installed Crane cams dual xr3000 boxes on 3 308's and we were told by the tech guys to run .50 gaps. i would call msd and ask, but Russ is the Guru, and i would try what he says, and go up from there. we had no issues with .050 and even .060 with the crane units. cars ran cool and clean.

    we used NGKBP6ES plugs. the 5's were a bit hot, and were only needed when the jets were wrong, or there were vacuum or exhaust leaks affecting one cylinder.
     
  5. luckydynes

    luckydynes F1 Rookie

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    #5 luckydynes, Aug 9, 2008
    Interesting . . . you guys haven't seen deterioating electrodes . .. any thoughts on why I was seeing that? I'm running the Denso coil on plugs with resistor plugs . .. could the spark be that much hotter?

    I'll post pics of it . . need to clean off the disk and make room.
     
  6. johnvwatts

    johnvwatts Formula Junior

    Jul 7, 2007
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    #6 johnvwatts, Aug 9, 2008
    Thanks for the input. The MSD's are the multiple spark type not the CD type. Just checked the gaps again and they are .050 not .045 but car is running much better than the stock .025. Jets are rich 155 mains, 55 idles, 180 a/c and plugs NKG 5's. Plugs appear to be running a nice grey colour. Noticed a mark increase in performance with the MSD's and the bigger gap when pared with the 155 main jets. Might try gap at .060 just to see but so far so good.
     
  7. thecarreaper

    thecarreaper F1 World Champ
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    #7 thecarreaper, Aug 10, 2008
    we were told not to use resistor plugs, hence no "r" in the NGK part number. the plug extenders were of the QV type, not the carb car ones, as the carb car extenders have a resistance value built into them.
     
  8. luckydynes

    luckydynes F1 Rookie

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    #8 luckydynes, Aug 10, 2008
    My coil on plug setup wouldn't work without resistor plugs . . . many calls to tech but I finally figured it out . .. almost threw away my MSD DIS4 and all the Denso coil on plugs and then it dawned on my there's no resistance period and it was screwing up the ECU crank trigger due to zero resistance . .. car idled fine but when you'd rev it she'd loose crank trigger.

    Any other thoughts on erroding electrodes? Is it that the DIS4 is hot? MSD told me I should run 2 of them so I'm not splitting the energy between 2 coils.
     
  9. thecarreaper

    thecarreaper F1 World Champ
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    #9 thecarreaper, Aug 10, 2008
    i hate to say it, but the truth hurts! i only keep my cars a year or so and move on to something else, so i never saw any erosion issues. i have maintained contact with all of the new owners, and have not had any calls on failures or problems.
     
  10. luckydynes

    luckydynes F1 Rookie

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    #10 luckydynes, Aug 10, 2008

    this happened over about a month at .055-.06 plug gap . . .don't think we're comparing apples to apples with coil on plugs and a dis4 to just an MSD.
     

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