Pontiac engine spark plugs

Discussion in 'High Performance Modifications' started by Fbird, Jul 15, 2019.

  1. Fbird

    Fbird Veteran Member Lifetime Gold Member

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    Ok been a LONG while since I had mine running but specs are:
    Pontiac 400 10.7 cr, RA IV cam ,#62 heads (alot of work there) Torker 1 intake, MSD 7AL ignition (25+ yrs old) MSD 10mm cables. These heads use the gasket type plug. Again it's been a LONG time (probably 6 yrs since i did plug in this). Motor is locked up currently (3 yrs now .. :( )
    I used to run #85 plugs gapped up to .110 ......yes BIG gap (PITA) but when i installed the MSD i was always lead to believe run as much gap as it will run....when it misses 1 time during trials...tighten back up by .010. That was about as big as I could get without killing the ground strap. Recently a friend and I were discussing this as he has a SBC (alot of SBC i might add) running a MSD 7AL (new digital stuff) as I asked him what he wanted me to gap his plugs at he said .045......???
    My Poncho consistently moved my 80 TA (fully loaded) 0-91 (ish) MPH in 8.2 sec (1/8 mile times) shifting 6100-6200. (he's running more like 9.20's 140 mph 1/4 mile in a 2900 lb NOVA)

    Am I off here or missing something. ?
     
  2. 77 cruiser

    77 cruiser Veteran Member

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    Big gap is hard on the ignition system, forces it to produce more voltage. .035-.040 is all you need.
     
  3. 1980RS

    1980RS Veteran Member

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    I run my gaps at .028 never had any trouble.
     
  4. COPO

    COPO Veteran Member Lifetime Gold Member

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    I run my gap at .035 with a MSD 6AL 6420. MSD wants you to run a wider gap so you burn up your box and go buy a new one. Great sales pitch.
     
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