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Does anyone "index" their spark plugs?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 73Jimmy, Jan 21, 2001.

  1. 73Jimmy

    73Jimmy Registered Member

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    Does anyone \"index\" their spark plugs?

    I heard that you get better performance if the gap on your spark plugs point toward the valves.
    You do this by "indexing" your plugs.. marking the gap side on the ceramic tip with a marker,
    then using shims as needed to make sure the mark points toward the valves when the plug is tight.

    Anyone else heard of this?

    Thanks,
    73Jimmy
     
  2. jimmyjack

    jimmyjack 1/2 ton status

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    Re: Does anyone \"index\" their spark plugs?

    Never heard of this, but I work with a speed freak and if anyone knows he would. When you say shim, you mean like a washer?

    creepin' and crawlin'

    Jim
     
  3. yeild2me

    yeild2me 1/2 ton status

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    Re: Does anyone \"index\" their spark plugs?

    we covered this while i was at wyoming tech. it is mostly used in high performance applications where every thing has to be EXACTLY right to get the absolute most you can. it is not worth the time and trouble to do on your daily driver, the benefits would probably not even be noticable. i did a high school term paper on Don Garlits, and he said when they did it, they bought boxes and boxes of plugs so they wouldnt have to use the shims. im sure top fuelers and tose guys still do it, but at wyo tech back in 91 was the last i have ever heard anyone talk about till now....

    AIRBORNE!!
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: Does anyone \"index\" their spark plugs?

    The local speed shop here has the shims for indexing plugs.
    My wife used to have an 86 Mustang GT, so first I bought a set of splitfires for it and then I indexed the plugs. It was just a little experiment on my part (when I had time for this crap, before the kids arrived[​IMG])
    Quite honestly I could not feel any difference from the Champion plugs that were in it (big surprise [​IMG]) and indexing was as much of a dud. I think you may gain something but not enough to actually notice.
    Keep in mind the only 'dyno' i used was my right foot and the seat of my pants.

    Rene

    [​IMG]
     
  5. BlazerGuy

    BlazerGuy 3/4 ton status

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    Re: Does anyone \"index\" their spark plugs?

    I saw that on Nascar Garage, I guess it would only make a difference in a vehicle like that.

    Murphy's Law :
    "When you don't know what your doing, do it neatly."
     
  6. gokartergo

    gokartergo 3/4 ton status Staff Member Moderator

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    Re: Does anyone \"index\" their spark plugs?

    I tried it on my gokart 10 hp bored out 30 over with bellet rod and custom made cam. With lieghtened flywheel and advaneced timing running on 110 octane leaded gas. It did not make any diffrence.
     
  7. HarryH3

    HarryH3 1 ton status Author

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    Re: Does anyone \"index\" their spark plugs?

    It's mostly used by the drag racer crowd. On a high performance engine, it can make a few hundreths of a second difference in the 1/4-mile. That's enough to mean the difference between winning and losing a race. Hardly worth the trouble for a daily driver.

    The idea is to make certain that there is nothing obstructing the path between the spark and the incoming air/fuel mixture by keeping the side electrode out of the way.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     

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