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Thread: Spark plug lead

  1. #1
    Join Date
    Dec 2019
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    amersham
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    265

    Spark plug lead

    Having just attached my AK manifolds i notice that in some instances the end of the spark plugs are close to the fabricated tubes, so close in fact that it may be necessary to remove the existing HT lead cap and find an alternative which will fit in the tight space. My initial concern was that there could be a chance of the spark plug arcing out to the manifold, but of course in theory with a good suppressing cap this should not happen.
    Anyone else had a similar problem ?.

  2. #2
    Join Date
    Aug 2004
    Location
    Christchurch, NZ
    Age
    60
    Posts
    2,509
    I don't think a supression cap has anything to do with arcing to nearby metalwork. The small right-angle silicon caps will survive for quite a while in extreme heat but will crack in the end. I'll grab a photo when my camera's charged...
    Cheers

    Myles D-W

  3. #3
    Join Date
    Aug 2007
    Location
    Bournemouth
    Posts
    652
    My leads are also extremely close to the headers which are wrapped. But in my case, unless there is direct contact, the leads wont burn with the wrap in place. I did get some contact earlier this year and it burned, so had to replace.

    David.
    David.

    Life is driving the Cobra. The rest of the time is just waiting................till I fix it!

    Wessex region caretaker rep.

  4. #4
    Join Date
    Nov 2012
    Location
    Lanarks
    Age
    65
    Posts
    698
    Google images
    TVR chimaera exhaust manifold and look at their spark plug shrouds

  5. #5
    Join Date
    Aug 2002
    Location
    Through the Darien Gap
    Posts
    1,069
    Assume this is a SBC. A typical issue with the design of the heads. Right angle leads are the way to go (and keep and eye on them and a spare or two in the boot).
    Steve Brown

    CRC Regional Rep - East Anglia

  6. #6
    Join Date
    Oct 2018
    Location
    Shipston-On-Stour
    Posts
    659
    Yep, all about the angle. I use 45 degree ones, suits my heads/manifold. MSD also do a long flexible one that you can essentially shape to whatever you need. They call it a multi angle terminal boot! Not tried them but they do look useful

  7. #7
    Join Date
    Feb 2010
    Location
    Essex
    Posts
    249
    Yep, been there and as said I also keep a couple in the boot. Also I use Spark plug lead heat shield sleeves and push them right up to the spark plug on my SBC rated to 1800 deg for extra peace of mind
    AK Gen 1, SBC 350, 3.54PL Diff, Getrag - Build Start 03/09/2010 Passed IVA 01/09/2014 On the Road 01/10/2014

  8. #8
    Join Date
    Apr 2014
    Location
    Stourport on Severn
    Age
    63
    Posts
    296
    You need spark plug lead heat Shields for those leads that are anywhere near the headers. I had an IVA fail where a lead had started to discolour/burn due to heat.
    Cheers
    Steve

    My missus asked me to build her a Cobra! – How good is that!

    AK Gen2 chassis arrived 12/2/15 IVA Passed 2/7/18 on road 29/7/18
    http://stevesakcobrabuild.blogspot.com

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