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Indexing Spark Plugs

Discussion in 'Performance' started by Barra, Mar 28, 2016.

  1. Barra

    Barra Member

    Messages:
    272
    Location:
    Brisbane
    Hi Folks,

    I have read all over the interweb that indexing spark plugs is a good thing (doesn't give miraculous gains, but doesn't hurt :)). While I understand how to index plugs, I am curious about the best position for the the open electrode in the VW 1800 motor. If anyone could advise (not sure I'll do it, just curious) using the simple diagram below, where should the electode strap face for each plug be positioned? For example, in the 12 o'clock position for plugs 2 and 4 ?

    Thanks in advance (pun intended),

    Barra


    Indexing plugs.jpg
     
  2. saabman

    saabman Well-Known Member

    Messages:
    4,888
    Location:
    Goulburn
    from memory the gap shold be directed to the exhaust valve . so in a type IV engine 1 towards the front 2 towards the rear, 3 towards the front and 4 towrads the rear.

    the inlet is the center of the heads
     
  3. cbus

    cbus Well-Known Member

    Messages:
    13,570
    Location:
    sunshine coast
    Wouldnt projected and v tip give a similar result?
     
  4. Alpal

    Alpal Moderator Staff Member

    Messages:
    9,036
    Location:
    Melbourne Bend of Islands
    I'll be the mug.. How do you align the plugs??
    They are hard enough to get in anyway!
     
    Squidy and StevieVW like this.
  5. saabman

    saabman Well-Known Member

    Messages:
    4,888
    Location:
    Goulburn
    Now I read the question again - the strap of the electrode should point towards the centre of each head.

    1 and 3 towards the rear
    2 and 4 towards the front.
     
  6. Alpal

    Alpal Moderator Staff Member

    Messages:
    9,036
    Location:
    Melbourne Bend of Islands
    Still the dill, how do you know they are aligned?
     
  7. oldman

    oldman Super Moderator Staff Member

    Messages:
    10,989
    Location:
    Avalon Beach NSW
    My guess Al, would be to put a dot, in texta, on the insulator showing the position of the electrode.
    When the dot is in the correct spot….once tightened….it's done.
    I'm also curious as to how much of a difference indexing would actually make……
    I would assume every other mech. component would need to be in absolutely tip top order for this to be worth considering…..?
    But hen, I'm a bit of a dullard, happy to be educated ;)
    Cheers,
    Mark
     
  8. gazman

    gazman Well-Known Member

    Messages:
    1,914
    Location:
    Perth WA
    Pretty minimal difference on a standard road car Mark, its an old trick for squeezing an extra pony or two out of a performance engine. We used to draw a line down the insulator in-line with the electrode, and use thin copper washers to shim them as needed...
     
  9. AC-T3

    AC-T3 Well-Known Member

    Messages:
    1,137
    Location:
    Woy Woy
    And just to be a pendant, a Type 4 motor would set cylinders 1 and 4 with the strap aligned to 225 degrees from vertical with 2 and 4 set at 135 degrees, giving a net gain of ………. hp ??????????? Nah, easier to go turbo.
     
  10. oldman

    oldman Super Moderator Staff Member

    Messages:
    10,989
    Location:
    Avalon Beach NSW
    Thanks Garth.....what I thought ;)
    Cheers,
    Mark
     
  11. Alpal

    Alpal Moderator Staff Member

    Messages:
    9,036
    Location:
    Melbourne Bend of Islands
    Doh! Too hard!!
     
  12. Barra

    Barra Member

    Messages:
    272
    Location:
    Brisbane
    Thanks Folks,

    I'll get around to that one day and let you know how many ponies are released (or parts thereof).

    Hahaha

    Barra
     
  13. oldman

    oldman Super Moderator Staff Member

    Messages:
    10,989
    Location:
    Avalon Beach NSW
    That'd be a dyno job methinks……
    Cheers,
    Mark
     

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