Results 1 to 9 of 9

Thread: Indexing Plugs?

  1. #1
    Senior Member MASTER BUILDER
    Join Date
    Aug 2007
    Location
    Iowa - USA
    Posts
    218

    Indexing Plugs?

    I assume that to index plugs in an engine, you true to orient the electrode the same in all cylinders. If I am correct, is there an easy way to do this seeing as how the headers block seeing the orientation of the plug.

  2. #2
    Senior Member DYNO OPERATOR
    Join Date
    Aug 2005
    Location
    Rifle Colorado
    Posts
    585
    The most important reason to index plugs is to prevent the piston dome from contacting the ground strap on the plug. If you don't need to do it, it isn't worth the effort. It usually doesn't matter if the ground strap is up, toward the front, or toward the rear, just not down.
    I use a sharpy to draw a line on the porclain on the ground strap side so I can see the orientation with the plug installed & tight. It may take a bunch of plugs to get a full set indexed without index washers........
    Johnny

  3. #3
    Senior Member MASTER BUILDER
    Join Date
    Aug 2007
    Location
    Iowa - USA
    Posts
    218
    The obvious question is what are index washers? Thanks for the sharpie tip.

  4. #4
    Senior Member DYNO OPERATOR
    Join Date
    Aug 2005
    Location
    Rifle Colorado
    Posts
    585
    You can get indexing washers from Jegs, Summit, ect. They're basically a shim that goes on the plug seat to change the position of the ground strap. If for a tapered seat plug, they're cone shaped, and flat for a gasketed plug. They look like a gsket and come in various thicknesses......I prefer to buy several sets of plugs at a time and find the correct one for each hole by trial and error. It can take a while and be kinda frustrating, but it beats smashing a plug at high rpm....the washers work fine though. I just don't like the idea unless I'm in a hurry.....or already tried 20 plugs and still haven't fould one that will work!!

  5. #5
    Senior Member RACING JUNKIE
    Join Date
    May 2003
    Location
    Coldwater, MI
    Posts
    2,998
    I use indexing washers seen no difference in doing it this way or buying several plugs and doing it that way. I put mine between 10-2 o'clock
    David Lanning
    IHRA NHRA 387B

    Fleenor Racing Transmission
    419-280-1406
    Lanning Electric
    Complete Drag Car Wiring
    APD Race Engines
    www.apdracing.com

  6. #6
    Senior Member MASTER BUILDER
    Join Date
    Aug 2007
    Location
    Iowa - USA
    Posts
    218
    It would seem to me that the use of diamond fire type plugs, that have 3 electrodes, would negate the need to index plugs. Have you ever tried these plugs?

  7. #7
    Senior Member DYNO OPERATOR
    Join Date
    Aug 2005
    Location
    Rifle Colorado
    Posts
    585
    Nope. I'm not a fan of "trick of the week" anything. You'd be money ahead to stay with a conventional plug in my opinion.....if they have 3 regular ground straps, they may hit the dome no matter how you index them.

  8. #8
    Senior Member MASTER BUILDER
    Join Date
    Aug 2007
    Location
    Iowa - USA
    Posts
    218
    Good point.

  9. #9
    Senior Member MASTER BUILDER
    Join Date
    Dec 2005
    Location
    Napier, New Zealand
    Posts
    230
    I bought a Moroso indexing nut. You just screw in an old plug that you know is indexed for a certain cylinder, mark the position on the nut, then find a new plug that screws into the same position. The nut is good and wide so you can mark a scratch on it and a cylinder number. A hell of a lot easier than indexing on the cylinder itself.

    Another reason for indexing, other than piston to plug clearance, is to ensure the spark is facing the gases and the strap is not going to interfere with any ignition of the gases or flame travel.
    It Ain't Over Til Its NOVA - 634ci of S*#t Your Pants!


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Email us - Support@RacingJunk.com
Call us - 866.326.9227
Copyright © 2005-2016 RacingJunk.com All Rights Reserved.

Designated trademarks and brands are the property of their respective owners. Use of this Web site constitutes acceptance of the RacingJunk.com
Terms of Use, Classifieds Disclaimer, Privacy Policy, and Cookie Policy