V12 - Single Dist Cap and Rotor

Discussion in 'Vintage (thru 365 GTC4)' started by enio45, Jul 8, 2018.

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  1. DWR46

    DWR46 Formula 3
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    Jun 19, 2012
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    Lancia: I believe the 195B in your photo is a single 12 cylinder distributor, with two coils (notice the external wire connectors). It is just a pair of six cylinder distributors in one housing. Each pair of points has one set to start the coil saturation and one set to end it.
     
  2. enio45

    enio45 Formula Junior
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    Ed
    I like the idea of getting the correct parts - to make it work. You had to so some significant research to
    get this far with your analysis. The price for the unit to get the shaft is pricey.....somewhere the parts must
    be available? I know a few alfa guys and will see what they have.....is the alfa marelli a special type distributor....

    Should i expect when i find an orig used one that it will be very pricey?
     
  3. John Vardanian

    John Vardanian F1 Rookie
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    Lancia, thanks for that picture, I'll keep it with that cap cutaway of yours. I wonder why the 128C got these. Did they have an excess in their racing stockpile?

    So far as availability, did the 6C Maseratis use this same type?

    john
     
  4. DWR46

    DWR46 Formula 3
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    John: The Maserati Six Cylinder is different, they fire two plugs at the same time.
     
  5. DWR46

    DWR46 Formula 3
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    Ed: Alfa GTA parts are rare and usually quite expensive. It will be much cheaper to get a Euro C/4 Cap and Rotor. You also need to preserve the advance curve currently in the original distributor, the Alfa is totally different.
     
  6. enio45

    enio45 Formula Junior
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    Yes i agree with you on this - i have a rotor on the way to me, ill do the measurements and mods
    and let you all know what we have.

    Any opinions on converting the two points in the Ellena Distributor to the electronic pickup's?
     
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  8. DWR46

    DWR46 Formula 3
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    Far quite a few years, pointless conversions were the way to go. However, over time, I am changing my thinking. World War II was won on points and condensers. The system is actually quite reliable, and will almost never leave you stranded by the side of the road if you have a screwdriver and a pair of pliers. There are no performance gains with pointless systems if the original system is set up correctly. I recently converted an original Bosch CD system in a Alfa Montreal to points and condensers (needed old style coils) and the car runs significantly better and starts instantly.
     
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  9. turbo-joe

    turbo-joe F1 Rookie
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  10. lancia

    lancia Formula Junior
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    Ed, Dyke, To clarify, the only item from the GTA unit you would use is the weight/cup and shaft, and the upper bearing cage. You would use the 195 DTEM-KS weights and cam, the weight pivot posts are the same I believe, and the advance curve is preserved original. Original GTA parts would indeed be a challenge to find. The reproduction GTA Marelli unit happens to be available I trust because of a demand for conversions to the twin plug head on Alfa GT's. As I mentioned I asked if the the shaft alone was available from several sources and got no follow-up. Dyke thank you for your comment on the four points 195, I understand that it is just like two 6 cylinder units in one. I have not encountered this unit on a road Ferrari, and just speculated that it must have special application; the four points points are doing half the frequency of physical opening compared to the two points arrangement, per rotation and 12 firings. Hence perhaps more durable. Would you know what kind of points arrangement is in a 335S for example which has two 12 lead distributors? John, You asked about Maseratis - a version of the 195 is used for the 6 cylinder 3500 GT, which has twin plugs.
     
  11. DWR46

    DWR46 Formula 3
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    Lancia: The four points in the distributor in the photos are doing the SAME frequency of openings as a twin distributor setup. Each set of points is opening and closing three times per shaft revolution, the same as a twin distributor installation. My speculation is that Marelli thought the single distributor setup would be less expensive for Ferrari, and offered it to them. However, in practice, it proved less reliable, so the factory spent the extra funds to go back to the six cylinder units.

    It so happens that I have rebuilt the engine from the 412 MI (a Hot Rod 335 Sport). Its ignition system is mind boggling. Essentially it uses two of the style distributors in the previous photo. Each distributor fires one spark plug in each cylinder. So you have 24 spark plugs, two distributors with four sets of points in each distributor and four coils (two coils connected to each distributor). The engine times like eight, three cylinder engines. We do it on a distributor machine, on the car it would be a nightmare. What a lot of people do not realize, and you rarely see correctly restored, is that Ferrari used different colored spark plug wires for each distributor to make it easier to trace the over 80 feet of spark plug wire used in the engine.
     
  12. John Vardanian

    John Vardanian F1 Rookie
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    Very well said.

     
  13. lancia

    lancia Formula Junior
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    Thank you Dyke, The use of the four-point arrangement in the Jano four-cam motors confirms what I thought would be the logical application. My comparison of the frequency of points opening was not against the typical twin distributor installation. I was comparing the 195 B with four sets of points/3-lobe cam against the 195 DTEM-KS used on 128C and early 128D, which has two sets of points and 6 lobe cam. For one revolution the two sets of points each open/close 6 times; twice the frequency for a point set in the distributor arrangement with four sets of points.
     
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  15. DWR46

    DWR46 Formula 3
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    Lancia: I agree completely. Just as an aside, I have NEVER seen a condenser require replacement in a Ferrari/Marelli distributor. I realize that many routinely replace the condensers, but I rarely see Marelli points with enough pitting to justify considering condenser replacement. The correct CE1E condensers have not been available many years anyway.
     
  16. BMWairhead

    BMWairhead Formula Junior

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    Ted
    This has been my experience with non Ferrari applications, too. In well over 100k miles of riding BMW motorcycles with points, the only condenser failure I've had was with a new condenser. I don't change them and I carry a known good used one in my tool tray.
     
  17. John Vardanian

    John Vardanian F1 Rookie
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    About the only thing that can go wrong with the condenser is if the lead breaks off. With a capacitance tester it's easy enough to check it at tune-up intervals. It typically reads 0.24-0.26uF.

    john
     
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