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Thread: Spark Plug Ohm Question

  1. #1

    Default Spark Plug Ohm Question

    I have an MSD 6EFI CD box, Blaster SS coil and 8.5mm Super Conductor wires. MSD says to run one or two steps colder plugs and start at OEM plug gap (.060” in my case) and open up .005” incrementally until spark is dialed. I currently have NGK TR55 plugs and can get them to Ohm out just fine. I picked up a set of ACDelco MR43LTS plugs which are one step colder than the R44LTS that people typically run in Vortec headed applications when they are trying to avoid platinum or iridium plugs. I can’t get a single one to Ohm out properly out of the set of eight. The NGKs give me a reading in the mid 4Ks immediately. If I touch the ACDelcos just right, I can get them to start dropping below infinite (OL), but not consistently. There is a gentleman on a Jeep website who apparently has extensive dyno knowledge with various plug manufacturers and won’t touch ACDelcos. I know this is a can of worms only rivaled by the ‘which type of oil’ threads, but any suggestions? I was thinking of NGK TR6 plugs, but don’t want something that starts with a gap .010” off of my end goal so I don’t end up with a seriously angled electrode.

  2. #2
    Join Date
    Nov 2014
    Location
    Ont. Canada
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    1,457

    Default

    I will not use AC Delco plugs. I had an issue with them many years ago. I was getting a misfire with them, even with new plugs. Changed to NGK and have not had a problem since. I was getting an open reading on a lot of the new plugs.

  3. #3

    Default

    Thanks 81, good to know I’m not going crazy. At least the NGKs are still made in Japan vs. ACDelcos made in China. Unfortunately, there is no copper equivalent to the TR55 one step colder with a proper gap. NGK told me to not use the TR6 as it starts at .040 and they do not recommend going more than .008” in either direction.

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    23,111

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    I only use NGK spark plugs. (Autolite spark plugs are good too.) NGK spark plugs & MSD Super Conductor wires have always worked well for me. The factory spark plug gap should be fine.
    http://forums.holley.com/showthread....4896#post54896 (Forum post with good spark plug information links.)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  5. #5
    Join Date
    Jan 2010
    Location
    Brisbane, Australia
    Posts
    1,593

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    I don't see why you would start at .060", and then open up in steps of .005".
    I haven't set a spark plug at .060" for over 30 years.
    NGKs for me in all my cars at .040" to .044".
    Plugs wear through a good operating gap before going bad.
    Why start good, to go bad? Gary
    Regards, Gary

  6. #6

    Default

    Yes, I'd start with a gap anywhere from .035" up to .045". Any copper core plug will do just fine with the MSD system. Just when you do buy plugs always check for hair line cracks on them or any other damage before installing.
    shake-n-bake

  7. #7
    Join Date
    Jan 2010
    Location
    Brisbane, Australia
    Posts
    1,593

    Default

    I also Ohm new spark plugs, saves a lot of heartache if a misfire occurs. Gary
    Regards, Gary

  8. #8
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    23,111

    Default

    Yeah, I started doing this a couple years ago.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  9. #9

    Default

    Same, same, but different.
    shake-n-bake

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