V12 - Single Dist Cap and Rotor

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

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  1. enio45

    enio45 Formula Junior
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    Hi there - I'm working thru some issues on my Ellena Project -

    I just acquired the correct single distributor for the car - so the dizzy's that came with the motor when i bought the car - the typical dual 85 type distributors will be replaced with the single dizzy unit etc.

    My question is related to the distributor cap and rotor. I see several types - some for 512 and other types - so my question is related to my problem, i need to get a new dist cap and rotor and does it matter as to the internals, where the rotor touches to the cap so long as they are matched and i wire the cap appropriately?

    Quite confused on this issue - appreciate the advise.
     
  2. Motob

    Motob Formula 3
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    Nov 11, 2003
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    You will be hard pressed to find a new cap and rotor for that distributor. I am unaware of any new reproductions. In the past I have had the originals rebuilt/repaired.
     
  3. turbo-joe

    turbo-joe F1 Rookie
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    romano schwabel
    the rotor never touches the cap, there is always a small distance between the rotor and the cap.
    you use 1 or 2 coils? there are inside 2 or 4 points? with 4 points you need 2 coils, with 2 points you may use also 2 coils or only 1, but if then only 1 one you may get problems with higher rpm, because the coil can not produce so much sparks except you will use a coil from a BB what is not so easy to get
    photo from the distributor would be great
     
  4. enio45

    enio45 Formula Junior
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    Ill get some pics - it is a two coil ignition...

    motob - where do u get caps and rotors rebuilt/repaired etc?
     
  5. 4redude

    4redude Formula Junior

    Jan 13, 2005
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    If the new distributor is a Marelli, I believe the rotor is from an Alfa GTA which was part number # 105.32.05.011.00/04.
     
  6. lancia

    lancia Formula Junior
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    The Marelli St. 195 DTEM-KS has two sets of points and the cap is set up for two coils. I believe there is a racing version of the early 195 with four sets of points.

    Read Dyke Ridgley’s excellent FML article on the internal arcing problems with the original 195 cap and rotor, and the simple modification you can make to adapt the later 365 GTC/4 Euro cap and rotor which has similar architecture, appearance and fits the same, but with better internal shielding. You have to adapt the orientation of the later rotor, with a sleeve to step down from 10 mm shaft to the earlier 8 mm shaft.

    Note that switching to the single distributor requires also the casting for the back of the right bank cylinder head for the camshaft to receive the small tachometer gear drive, and the right cam has a different fitting on the end to drive the tang of the tach drive.
     
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  8. enio45

    enio45 Formula Junior
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    Excellent - which article if you recall - date?
     
  9. enio45

    enio45 Formula Junior
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    Here are pics of my recently acquired distributor. It has two points, 6 lobes and Marelli St. 195 DTEM-KS.

    I have 3 caps and 1 rotor that i collected...one cap is NOS but of a different inside type with no rotor for it.

    The other 2 caps are used, need cleaning buy look pretty nice inside, no cracks etc. The used caps use the same rotor you see in the picture. Obviously the rotor is not interchangeable with the NOS Cap.

    From all indication that i have found, the used caps and the rotor is the orig type for my car and this dizzy.

    If i was to find the proper rotor for the NOS cap, can i install that on the dizzy?
     

    Attached Files:

  10. DWR46

    DWR46 Formula 3
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    Ed: I wrote the article in the November 26, 1988 issue of the FML., and is included in the Tech Tips book. If you do not have a copy of my FML Tech Tips Book, you might want to find one. It covers lots of these items. I think they may still be available from the FML.
     
  11. enio45

    enio45 Formula Junior
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  12. enio45

    enio45 Formula Junior
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    OK got the article - thank you Cathy!

    good info - so my NOS cap looks to be the 365 cap - so to improve the performance i need to get the correct rotor and do the mods as suggested.....let me look into this.....

    Dyke, so the rotor mod is drilling a new hole in the rotor, not the dizzy shaft - correct?
     
  13. DWR46

    DWR46 Formula 3
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    Ed: I am pretty sure we used to drill the new holes in the shaft, as the Rotors have a metal "plug" in only one plane, so drilling on the Rotor and securing it to the shaft without the reinforcing "plug" is not a good idea.
     
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  15. enio45

    enio45 Formula Junior
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    Anyone have a un-used 365 GTC4 rotor they would like to donate?

    I would like to use it for design and experimentation before I buy a new one to do the mods .
     
  16. DWR46

    DWR46 Formula 3
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    Ed: You need the rotor for an EUROPEAN GTC/4. Only they have the single distributor. I used to buy them from GT Car Parts.
     
  17. enio45

    enio45 Formula Junior
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    ok, let me call bill tomorrow to see what he has
     
  18. enio45

    enio45 Formula Junior
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    Dyke, per your tech tip article, looks like the new rotor gets drilled for a new location to realign the
    same firing position as the original style rotor. This will be interesting.....

    The part number of the rotor you have in your article - Ferrari # 95300315 i assume is the one
    you reference above for the EUROPEAN GTC/4?
     
  19. John Vardanian

    John Vardanian F1 Rookie
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    I've had this picture for a long while and cannot remember where I got it, but I think it tells the story of how this type of distributor works. Essentially, it is a double decker.

    john

    Image Unavailable, Please Login
     
  20. Lowell

    Lowell Formula Junior
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    Out of idle curiosity, how should these single distributor caps be numbered?
    As far as I know, the two distributor engines had the two caps each numbered 1-6 clockwise with no regard to firing order.
     
  21. enio45

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    Lowell, good question as my 3 caps in my above pics have different numbering sequence starting at the hole next to the coil wire.
    However - it is number 1-12.

    I was heading that way to ask that question as soon as i get this rotor issue sorted.

    John, great picture - tells the story....i like the update version as you have pictured vs the orig design rotor and cap that
    i currently have. Ill get a later style rotor and see what mods are needed to make it work - then off to the firing order!
     
  22. Smiles

    Smiles Moderator
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    What a great thread.

    I was only aware or the dual distributors!

    Matt
     
  23. DWR46

    DWR46 Formula 3
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    Ed: I guess I should read my own article. Yes, follow the directions in the article and bore the rotor.
     
  24. afwrench

    afwrench Formula Junior
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    Hi guys ,I have a Euro 365gtc4.The cap # system can be confusing. Tower marked # 1 goes to cyl #1.After that you follow the firing order.Tower #2 goes to the next cyl that fires ,I think # 11 .I dont have the order in front of me.# 3 tower goes to the third cyl that fires and so on.Also dont mix up the coils. Mike
     
  25. enio45

    enio45 Formula Junior
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    NP Dyke......your advise is invaluable to us guys with way less experience!

    Im learning fast!
     
  26. lancia

    lancia Formula Junior
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    Ed, Dyke, John,

    That is my picture of the sectioned cap. I carefully cut an old cap to examine the relationship of the rotor gaps to the cap. The reason I did this is because I am testing a further development of Dyke's modification. The later distributor rotor is based on a distributor shaft design that is 10 mm diameter over its entire length. The early 195 DTEM-KS distributor is 10 mm diameter at the cam, stepping down to 8 mm at the rotor. The basic architecture of all these Marelli distributors is very similar from the late 1950's through the 60's. After lots of searching, I discovered that the Alfa Romeo GTA Marelli distributor has similar pieces and looking at an exploded picture of all the parts of the GTA unit, I realized that the shaft and cup for the weights, as well as the taper shaft for the nut, are the same fundamental design. But the GTA also uses the later style rotor and the shaft is 10 mm all the way. Better still the orientation of the posts for the weights, relative to the threaded screw hole in the shaft for the rotor gives you the same rotor orientation that you need for 195 DTEM-KS with no modifications at all - no drilling, no sleeves I puzzled over this). The height of the shaft is the same and the cap and rotor fit in the proper relationship just like the picture. .If you swap the GTA cup and shaft into the earlier 195, use the 365 GTC/4 EURO cap and rotor, all the pieces fall into place - at least on paper You can buy today at reproduction Marelli GTA distributor to get the parts - the cup/shaft and the upper bearing cage for the 10 MM shaft. The trouble is that the GTA unit - I got one from A.F.R.A to test this - is not cheap, set you back almost $2,800, but I was determined. Have not seen the cup/shaft available alone, I asked. I have not carried this out to full realization yet, but, unless I missed something along the way, it looks like it will work just right, no guarantees. I share the idea for you.

    Chris
     
  27. lancia

    lancia Formula Junior
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    P.S.

    Here is a picture of a Marelli distributor marked 195 B. I think it is a racing unit used in pairs for 4 coils, 24 plugs. 4 sets of points stuffed in there, 3-lobe cam. Image Unavailable, Please Login
     

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