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Spark Plug Wires & Extenders

Discussion in 'Technical Q&A' started by GeoMetry, Jun 18, 2008.

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  1. GeoMetry

    GeoMetry Formula Junior

    Apr 14, 2008
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    #1 GeoMetry, Jun 18, 2008
    Last edited by a moderator: Sep 7, 2017
    I have an 85 308. I have not really checked the wires to see if they need to be replaced but they sure look old. I don't know what the piece (pictured below) at the plug end of the wire that keeps the water out is called. I think it is called a "boot" so that is how I will refer to it in this post. Please correct me if I am wrong. All of the boots are OK except the one pictured. I get the impression that if I make a new set of wires I need to transfer those boots to the new wires. Is that correct? Can I buy replacement boots? There is a lot of discussion about plug wires here and a lot more information out on the internet from various vendors. There are many types of spark plug wires solid core, carbon core, spiral wound, dual core. I guess a good place to start is with what was originally installed. I believe the OEM wires were pretty standard carbon core, is that correct? I like the advantages associated with spiral wound wires but I read that some of them are not manufactured well. I see one of our fellow fchatters sells some ignition wire by the foot. Is that a good option?

    Next question is about the spark plug extenders. Red, Black, what is the difference? I have black ones, is that correct for my car? They look so simple it seems odd that they would ever need to be replaced. How can I tell if they need to be replaced?

    I am saving up for a 30K service so I want to keep expenses down as much as it is reasonable to do so. However if I leave these wires on I would bet that the dealer will replace them as part of the 30K service and I will pay the dealer price for the wires which will drive up the price of the 30K service.
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  2. BigTex

    BigTex Seven Time F1 World Champ
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    #2 BigTex, Jun 18, 2008
    Last edited: Jun 18, 2008
    That's the seal for the spark plug well....I know Trutlands sells them apart from the wire sets, possibly Ricambi America does as well.

    I have black extenders on all my early 308s.

    As far as age if you are not experiencing a misfire they are most likely fine, and while many do make wires it's pretty time consuming...I think Trutlands offers a kit to do the whole motor plus coils and includes the extenders and seals also for that TOTAL fresh feeling! LOL!

    That extender looks in great shape, I clean any rust off of the bottom spring clip inside and spray them with a Krylon clear ignition sealer to check for heat cracks, if one shorts or carbon tracks it'll be obvious then......they aren't very expensive but like your wires no point in throwing away good ones...

    Keep saving for your service and go with your Tech's advice at that time, IMO.

    Order a set of seals only now and put them on as rainwater in there is why the extenders overheat in boiling water or rust from the moisture....shorts the plug itself too, sometimes.
     
  3. Ricambi America

    Ricambi America F1 World Champ
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    #3 Ricambi America, Jun 18, 2008
    Yes, we have them. The full set of QV wires is $525.
     
  4. BigTex

    BigTex Seven Time F1 World Champ
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    #4 BigTex, Jun 18, 2008
    You da man.........you have the old black teeny weeny straight plug well seals for the 76- 77s??

    All of mine are LONG GONE! LOL!

    My plugs come out looking like a 'marine' application.....ugh!
     
  5. BigTex

    BigTex Seven Time F1 World Champ
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    #5 BigTex, Jun 18, 2008
    That's a good price, IIRC another local vendor here wants $325 per side.....:D
     
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #6 Steve Magnusson, Jun 18, 2008
    Last edited: Jun 18, 2008
    No, the stock ignition wires are a spiral wound fine wire construction -- about ~700 ohms/foot (and probably also has some non-zero inductance, but have never measured or seen a value given).

    (And you need some impedence in the wire+extender+plug combination to not damage the output transitors in your Digiplex units, if your 308QV is still so equipped)
     
  7. GeoMetry

    GeoMetry Formula Junior

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    #7 GeoMetry, Jun 18, 2008
    So since it came with spiral wound spark plug wires that pretty much tells me that is what I need to replace them with. That narrows things down quite nicely. Magnecor makes spiral wound wire sets for my car for $507. That seems a bit steep. I will have to call around a bit. I searched the forums and did not find any negative comments about the Magnecor wire sets. BigTex, I looked at the places you suggested for the "seal" and guess what... they call it a boot, but they don't have pictures so I have to call to see if they match because Magnecor sells the wire set for quite a bit less without the "spark plug boot and tube". Guess I may as well call the dealer too just for grins.

    What about Red VS Black extenders, what is the difference (other than color) and do I have the correct extenders for my car? I have black extenders on my 85 308 QV.
     
  8. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #8 Steve Magnusson, Jun 18, 2008
    Not necessarily -- what you want to match is the ohms/foot value (i.e., I wouldn't use a sprial wound wire that was 0 Ohms per foot)

    I don't know what the resistance value for your extenders should be, but I believe that the stock ones (used with the Digiplex) should not be 0 Ohms extenders. IIRC, people have mentiond values like 2 KOhm or 10~11 KOhm -- why not measure yours and give us another data point?
     
  9. spiderseeker

    spiderseeker Formula 3

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    #9 spiderseeker, Jun 18, 2008
    Last edited: Jun 18, 2008
    My 85' QV has red extenders, they are very low resistance but I don't remember what it was, I checked them last year when I changed plugs and they all had similar low resistance.
    (I thought the black extenders where higher resistance and used on the older (non-qv) cars)
     
  10. eulk328

    eulk328 F1 Rookie

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    #10 eulk328, Jun 19, 2008
     
  11. GeoMetry

    GeoMetry Formula Junior

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    #11 GeoMetry, Jun 21, 2008
    I guess I don't know what I am doing. My multimeter has several setting for measuring ohms (200, 2K, 20K, 200K, 2M) I tested with each setting and this is the results but I have to admit I don't understand what I am seeing.

    200 - 0.1
    2K - .001
    20K - 0.00
    200K - 00.0
    2M - .000

    I think that says almost no resistance at all. Am I doing something wrong?
     
  12. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #12 Steve Magnusson, Jun 21, 2008
    Last edited: Jun 21, 2008
    No, you are not -- it says they are essentially 0 Ohm connectors (and does maybe prove that color means nothing if spiderseeker's red ones are also 0 Ohm). I have no information on whether or not if that's correct for your model so my belief about ALL Digiplex-equipped 308 using non-zero Ohm extenders is probably wrong -- I'd just like us to get the facts better known on this stuff so would like to see any data on what a non-zero value might be and what model/version it is used on.

    E's 328 and my TR use a MicroPlex ignition -- which uses a 0 Ohm extender.
     

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