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  •  » spark plug recommendation

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    1/31/2019 6:02 PM  #1

    1fststang
    I FYI 24-7

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    Registered: 6/02/2013
    Posts: 419

    spark plug recommendation

    Looking for some recommendations on what plugs to run in my engine.

    Dart SHP block, Internally balanced and stroked to 427.  Has about 10 to 1 compression with AFR 205 (58cc) heads, roller cam, msd ignition.

    AFR paperwork says to use Autolite 3924 as a starting point.  Seems like I had heard more bad than good about Autolite.  Any recommendations?


     

     

    1/31/2019 6:12 PM  #2

    Raymond_B
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    From: Fort Worth, TX
    Registered: 4/01/2013
    Posts: 1,212

    Re: spark plug recommendation

    I've always used Motorcraft or NGK (not the fancy metal ones, just normal copper). In my 427 I used NGK 3696 (BKR6EY). Never really heard issues with Autolite, but never used them either. 
     

    Last edited by Raymond_B (1/31/2019 6:17 PM)

     

    1/31/2019 10:25 PM  #3

    Bolted to Floor
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    From: Houston, Texas
    Registered: 4/01/2013
    Posts: 2,018

    Re: spark plug recommendation

    I’m good with Autolites, used them in the past in multiple cars. The 3924 is what was recommended for the aluminum heads I got from Survival Motorsports. Never had an issue with Motorcrafts either. Can’t remember if the BMW got NGK’s or Bosch.

    John  -- 67 Mustang Coupe 390 5 speed
     

    1/31/2019 11:06 PM  #4

    6sally6
    Hyper FYIFORD ADDICT

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    From: Surfside Beach,SC
    Registered: 4/02/2013
    Posts: 6,874

    Re: spark plug recommendation

    Those or Champion.....which ever is on sale.
    Not a nickels worth of difference between any of them!
    Just like guys that "swear by" (fill-in-the-blank) oil/gas whatever.
    Plugs, oil, fuel, its all to such high standards they are all nearly identical.
    (For our "older" iron)
    6sally6

    Last edited by 6sally6 (2/01/2019 4:13 PM)

    Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
     

    2/01/2019 7:28 AM  #5

    TKOPerformance
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    From: Newark, DE
    Registered: 12/15/2014
    Posts: 7,526

    Re: spark plug recommendation

    I would advise running what the head manufacturer wants you to run.  AFR did tons of testing before making those recommendations.  I used all their recommended components when building my 331.

    A copper core plug is preferable in all but forced induction applications in my experience.  The platinum plugs are really just designed to live a long life, and don't provide as good a spark as regular old copper.  In forced induction applications copper just won't hold up very long and you're best using iridium. 

     

    2/01/2019 10:02 AM  #6

    lowercasesteve
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    From: Auburn, Ca
    Registered: 4/01/2013
    Posts: 1,256

    Re: spark plug recommendation

    Bolted to Floor wrote:

    I’m good with Autolites, used them in the past in multiple cars. The 3924 is what was recommended for the aluminum heads I got from Survival Motorsports. Never had an issue with Motorcrafts either. Can’t remember if the BMW got NGK’s or Bosch.

    Back when I had my Honda S2000 they said to use Bosch, Not NGK.  I made a mistake and used the NGK's.  Engine ran like crap.  returned to the Bosh's and all was well.

    My take away? Use what the maker recommends.
     

    Original owner - 351w,T-5, 4whl disks, power R&P
     

    2/01/2019 10:12 AM  #7

    TKOPerformance
    Hyper FYIFORD ADDICT

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    From: Newark, DE
    Registered: 12/15/2014
    Posts: 7,526

    Re: spark plug recommendation

    lowercasesteve wrote:

    Bolted to Floor wrote:

    I’m good with Autolites, used them in the past in multiple cars. The 3924 is what was recommended for the aluminum heads I got from Survival Motorsports. Never had an issue with Motorcrafts either. Can’t remember if the BMW got NGK’s or Bosch.

    Back when I had my Honda S2000 they said to use Bosch, Not NGK.  I made a mistake and used the NGK's.  Engine ran like crap.  returned to the Bosh's and all was well.

    My take away? Use what the maker recommends.
     

    Japanese engines in particular are VERY sensitive about what plugs you run.  I've never had any luck running anything other than the stock plug in them.  The only deviation from this was running a slightly colder plug in my WRX because I kept melting the tips off the stock heat range due to the modifications I made to the engine. 

     

    2/03/2019 5:55 PM  #8

    1fststang
    I FYI 24-7

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    Registered: 6/02/2013
    Posts: 419

    Re: spark plug recommendation

    Well I guess I'm going to give the Autolite they recommend a try. At 2.50 each can't go to wrong.

    What gap are you guys using with good luck with MSD distributor and 6AL spark box?  

       •Thread Starter
     

    2/03/2019 6:19 PM  #9

    TKOPerformance
    Hyper FYIFORD ADDICT

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    From: Newark, DE
    Registered: 12/15/2014
    Posts: 7,526

    Re: spark plug recommendation

    Depends mostly on the coil IME.  With a typical high energy ignition I woun't start any lower than 0.045, but have gone up to 0.065 on some engines with no issues and great performance.  HEIs with 50,000 volt coils we used to run 0.055, and on the Mustangs with the Screamin' Demon coils we used to run 0.065".

    Its all about the combination though.  You need good, low resistance plug wires to run big gaps (Livewires, MSD Superconductors, etc.).  Then a good coil that can throw 50k volts or more. 

     

    2/03/2019 9:59 PM  #10

    6sally6
    Hyper FYIFORD ADDICT

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    From: Surfside Beach,SC
    Registered: 4/02/2013
    Posts: 6,874

    Re: spark plug recommendation

    .055
    6s6

    Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
     

     

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