Which NGK plugs and gap for 71 455

Discussion in 'Street/strip 400/430/455' started by FJM568, May 15, 2023.

  1. FJM568

    FJM568 Well-Known Member

    Which NGK plugs and gap for 71 455 with Dave Ray Ignitionman small body HEI...stock iron heads, TA288-94 cam, about 9.5:1 comp, etc?

    The 6630's? Do I run the points gap or the HEI gap? Or somewhere in-between?

    Thanks!
     
  2. Mark Demko

    Mark Demko Well-Known Member

  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

  4. CJay

    CJay Supercar owner Staff Member

    Whats the advantage with an NGK vs the AC 44TS?
     
    Mart likes this.
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The NGK plug has more of a projected nose. It places the spark closer to the center of the combustion chamber. This has an effect like advancing the timing. Projected nose plugs, in theory, have a wider heat range. They run hotter at low RPM, and cooler at higher RPM, again, in theory.

    https://help.summitracing.com/app/answers/detail/a_id/5080/~/spark-plug-insulator-type


    https://www.rockauto.com/info/341/19354427_Primary.jpg

    https://www.rockauto.com/info/100/NGK6630-2.jpg

    https://www.amazon.com/Champion-Copper-Plus-Spark-RV17YC/dp/B07N156F88

    The electrodes on the NGK V Power plugs have more sharp edges. The spark likes sharp edges. NGK plugs have plated threads. That is a clear advantage in an aluminum head. No anti seize is required. Anti seize can interfere with heat conduction, and some think, if a little is good, more is better.:)

    Bottom line is an engine's plug needs and results require some experimentation. I remember back in the day trying the Champion RV17YC plugs in my 72 Skylark 350 after using the AC R45TS plugs. The engine felt snappier to me, I could feel the difference. They had noticeably more of a projected nose. Results can vary.
     
  6. Guy Parquette

    Guy Parquette Platinum Level Contributor

    Correct. The projected plug not only has that effect, in reality it IS advancing the timing. Also, it “packs” the combustion chamber slightly giving a bit more compression. We used the projected plugs in our stock class race sleds where they tore us down at every race to check specs.
    We also dyno’d plugs and the projected tip plugs always showed a slight increase in HP.
     
  7. 2.5

    2.5 Platinum Level Contributor

    Interesting info here guys. Thanks for posting this.
     
    FJM568 likes this.
  8. Guy Parquette

    Guy Parquette Platinum Level Contributor

    I may explain a little further on what Larry is saying. The spark ends up closer and down further to the up coming pistons. So the spark ignites not sooner but physically deeper, in the combustion chamber which advances the time it fires everything. It will show more of an improvement on a Hemi style head like our snowmobile engines…
     
    Last edited: May 18, 2023
  9. Mart

    Mart Gold level member

    I run the R44TSX with extended tip, gapped at .060
    Ran the R45TSX for a year, they are one range hotter.
    Both run clean.
     
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The AC TSX plugs have a longer ground electrode for larger gaps. The nose is the same. So a R45TSX is the same plug as a R45TS, just a longer ground electrode.

    NGK adds another 5 to the part number for the longer ground electrode, so a UR-45.

    https://www.rockauto.com/en/parts/ngk,6945,spark+plug,7212

    The gap is preset to .060. NGK says you can open or close the gap .008 without affecting the perpendicularity between the center and ground electrodes. So you want to order the correct plug according to the gap you intend to run
     
  11. 2.5

    2.5 Platinum Level Contributor

    Would the plug for a 70 car require a different plug than a 71 because of compression differences or are there other factors that that are at play?
     
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Maybe, but being our engines are usually modified, factory recommendations go right out the window. Rule of thumb is to run the coldest plug that doesn't foul. Some experimentation is mandatory I'm afraid. Usually, a slightly colder plug works great. That would be an R43TS, or an NGK UR-5.
     
  13. Mart

    Mart Gold level member

    Aren't larger gaps for high energy ignition such as MSD?
     
  14. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    In general, but static compression, forced induction, and nitrous are all considerations. The more cylinder pressure there is, the harder it is to jump the gap. You'll know if you go too big on gap.

    Bigger isn't always better.:)
     
  15. Quick Buick

    Quick Buick Arlington Wa


    Last set of NGK were make in USA..

    Last set of AC plugs were made in Chyna.
     
  16. dentboy

    dentboy stacy kelevra

    The coating on a ngk ground strap burns really clean to see a definitive point to see if motor likes where timing is set at
     
    Guy Parquette likes this.
  17. Guy Parquette

    Guy Parquette Platinum Level Contributor

    you are absolutely correct. Again…I keep referring to our race snowmobile engines, but it relates. On our imp. Stock and pro stock sleds where the rules are opened, we ran 15.5/1 compression. Had to tighten up the gap otherwise the engines would break up under load as is going down the track and on the dyno.
     
  18. 70 GMuscle

    70 GMuscle Plan B

    I recommend NGK UR5. Use them in my 73 455 a little warmed over. Cooler than a UR4.
     
  19. Mart

    Mart Gold level member

    So super high compression snuffs out the flame. I could see that happening. So far, I have no breakup at 11-1. I would think polished chambers, radius all sharp edges on valves, pistons, etc. helps. Fox said go down in heat range so I went to 44's instead of 45's. :D
    I also noticed newly made AC plugs come from Mexico. I have a coffee can full of Flint, MI assembly line plugs...the good ones..:)
     
    Mark Demko likes this.
  20. Mark Demko

    Mark Demko Well-Known Member

    Same as the Turbo Regals, IIRC, at the factory 14 lbs. boost they’re gapped at .032
     
    Guy Parquette likes this.

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