News

What kind of spark plug wires to use?

Discussion in 'Technical Q&A' started by Ak Jim, Aug 10, 2019.

  1. Ak Jim

    Ak Jim F1 Veteran
    Rossa Subscribed Owner

    Dec 23, 2007
    5,320
    North Pole AK
    Just wondering what kind of plug wires for a 1975 Ferrari 365GT4. This is a dual distributer engine using Pertronics pickups in place of the points and their matching coils.
     
  2. To remove this ad click here.

  3. absostone

    absostone F1 Veteran
    Silver Subscribed

    Jul 28, 2008
    5,630
    What does pertronix recommend?
    I would start there.
     
  4. Ak Jim

    Ak Jim F1 Veteran
    Rossa Subscribed Owner

    Dec 23, 2007
    5,320
    North Pole AK
    Good idea, I will check their website.
     
    absostone likes this.
  5. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,903
    Texas
    Full Name:
    Steve Magnusson
    One thing to consider is that the hole in the stock distributor cap is designed for a 7mm diameter spark plug wire (not 8mm diameter). The stock wire uses a spirally wound fine wire construction (I'd stay with that type of construction vs a carbon impregnated core or solid large straight wire -- JMO).
     
    Peter, f355spider and Ak Jim like this.
  6. Ak Jim

    Ak Jim F1 Veteran
    Rossa Subscribed Owner

    Dec 23, 2007
    5,320
    North Pole AK
    I looked at the Pertronix website and that is the kind of 7mm wire they have. Sent them am email asking about putting a set together for me. I've been using the carbon core and it's been ok, just want to see if I can make the car run even better.
     
  7. To remove this ad click here.

  8. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    2,182
    Berkeley, CA
    Full Name:
    Brian Brown
    I would recommend using the OEM wires (made using Cavis 400), which are a spiral wound wire ( as Steve suggested).
     
  9. JCR

    JCR F1 Veteran
    Silver Subscribed

    Mar 14, 2005
    7,275
    H-Town, Tejas
    Peter likes this.
  10. Ak Jim

    Ak Jim F1 Veteran
    Rossa Subscribed Owner

    Dec 23, 2007
    5,320
    North Pole AK
    Everyone thanks for the suggestions.
     
  11. tbakowsky

    tbakowsky F1 World Champ
    Professional Ferrari Technician Consultant

    Sep 18, 2002
    15,391
    The Cold North
    Full Name:
    Tom
    Peter likes this.
  12. To remove this ad click here.

  13. APA#1

    APA#1 Formula 3
    Rossa Subscribed

    Nov 5, 2003
    1,222
    Central Florida
    Lowest ohms are generally the best, unless your specs are otherwise, 50 ohms as a rule. After that quality, price, fitment etc.
     
  14. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    2,182
    Berkeley, CA
    Full Name:
    Brian Brown
    This is not true. The OEM spiral wound wires will be in the 1K (1000) OHM range depending on the length of the wire.
     
  15. APA#1

    APA#1 Formula 3
    Rossa Subscribed

    Nov 5, 2003
    1,222
    Central Florida
    As I mentioned, unless specs are otherwise
     
  16. Peter

    Peter F1 Veteran
    Rossa Subscribed Owner

    Dec 21, 2000
    6,401
    B.C., Canada
    Available in red though? I've got a bulk roll of black cable and have made sets, but the original Cavis wires were red... I've found it much harder to find 7mm wires (either as a pre-made universal set, or a bulk roll) in red.

    8mm is certainly more available. When Ferrari switched to Digiplex ignition with the first injected cars, what size of wires were they? Still 7mm? Or if they switched to 8mm, can I just use those caps and rotors?
     
  17. waymar

    waymar Formula 3

    Sep 2, 2008
    1,098
    Northeast, PA - USA
    Full Name:
    Wayne
    My 1982 308GTSi has 7mm.
     
    Peter likes this.
  18. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,903
    Texas
    Full Name:
    Steve Magnusson
    #15 Steve Magnusson, Sep 2, 2019
    Last edited: Sep 2, 2019
    Ferrari went down a different design path by staying with the 7mm diameter spark plug wire but adding a separate outer red silicone insulation tube (introduced on the 308QV, I think, but used on the later Microplex-equipped models, too) to deal with the higher secondary voltages; whereas, the spark plug wire makers added the extra silicone insulation into the wire itself (which was what drove the diameter up to 8mm). Consequently, all of the Digiplex and Microplex caps still need the 7mm diameter spark plug wire size, too.

    Interesting point about your needing red -- is that only an "early" 308GT4 thing, or all years 308GT4? AFAIK, all 308B/S and TR use black.
     
    afterburner and Peter like this.
  19. Ak Jim

    Ak Jim F1 Veteran
    Rossa Subscribed Owner

    Dec 23, 2007
    5,320
    North Pole AK
    Just an update. I contacted Pertronix. They have the spiral wound wires (in black) that have less resistance then the carbon conductor wires. I got two 6 cylinder universal sets that have the spark plug boot attached at the factory. Cost with shipping was around $85. I'll install these sometime this winter.
     
    Peter likes this.
  20. absostone

    absostone F1 Veteran
    Silver Subscribed

    Jul 28, 2008
    5,630
    ive been looking into NEW wires recently . I have bosch optilayer mag core wires that I made around 2003-ish Always ran great, with my XR700 setup, was looking at the Pertronix ires today. is this a good match ?
     
  21. Peter

    Peter F1 Veteran
    Rossa Subscribed Owner

    Dec 21, 2000
    6,401
    B.C., Canada
    AFAIK, they're all red.

    The set I have on my car now are black as they're ones I made from a bulk roll... Many years ago. A moot point now as I just purchased a complete, red, 7mm set from one of the suppliers.

    That's interesting to learn that Ferrari (or I suppose Cavis supplied?) an insulating sleeve over the wiring.
     
  22. absostone

    absostone F1 Veteran
    Silver Subscribed

    Jul 28, 2008
    5,630
    I don’t believe they were red
     
  23. Peter

    Peter F1 Veteran
    Rossa Subscribed Owner

    Dec 21, 2000
    6,401
    B.C., Canada
    Which, for our GT4s?
     
  24. absostone

    absostone F1 Veteran
    Silver Subscribed

    Jul 28, 2008
    5,630
    yes ive never seen that factory,
     
    Peter likes this.
  25. Ak Jim

    Ak Jim F1 Veteran
    Rossa Subscribed Owner

    Dec 23, 2007
    5,320
    North Pole AK
    Don't forget there are two kinds of GT4s
     
  26. Peter

    Peter F1 Veteran
    Rossa Subscribed Owner

    Dec 21, 2000
    6,401
    B.C., Canada
    You mean 208 and 308, or Euro and U.S. spec?
     
  27. Peter

    Peter F1 Veteran
    Rossa Subscribed Owner

    Dec 21, 2000
    6,401
    B.C., Canada
    FWIW, I knew I had this photo in my files on my PC. It was taken by the original owner of my car, just prior to when he traded it in, back in 1977.

    When I bought the car in 2000, it had red, Cavis wires. I can't say for sure it was the same set, but they were red and I kept them.

    Image Unavailable, Please Login
     
  28. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,903
    Texas
    Full Name:
    Steve Magnusson
    You know, Peter, I'm starting to now think that all the 308 carb (at least US) had the red wires. Here's a shot of my ex-308 -- not the original wires, but bought as a set from a well-known supplier way back (PartSource?), and it included the metal guide fittings and rubber grouping rings like on yours:
    Image Unavailable, Please Login
    Maybe they didn't go black until the 2Vi cars?
     
    Peter and waymar like this.

Share This Page