Single Distributor Cap differences between points and electronic? | FerrariChat
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Single Distributor Cap differences between points and electronic?

Discussion in '308/328' started by bitsobrits, Jun 4, 2022.

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  1. bitsobrits

    bitsobrits Formula Junior
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    Nov 12, 2011
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    Steve
    #1 bitsobrits, Jun 4, 2022
    Last edited: Jun 4, 2022
    I recently fitted a single distributor conversion using the 123+ Ignition electronics. I'm having issues with sporadic spark on the 1-4 bank, and everything seems to check out except the cap and rotor which I'm not sure how to check (visual looks okay). So I was going to order spares for each, but see there are two caps listed for the dual coil single distributor housing; one for points and one for electronic. Anyone have an idea what the difference between the two could be?

    Edit: more internet searching reveals the electronic version has a couple of slots for sensor leads at the base of the cap.
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    #2 Steve Magnusson, Jun 5, 2022
    Don't see "Ferrari" on the 123 ignition website -- is your system:

    Stock F single distributor fitted with two 123 modules mounted 135 deg apart
    Stock F single distributor cap
    Stock F double-ended rotor for single cap

    or are the cap and rotor aftermarket?

    Is the 1-4 bank using the not-center coil connection on the cap?

    I take it that you've tried swapping the two 123 modules (and two coils) with no change?
     
  3. bitsobrits

    bitsobrits Formula Junior
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    #3 bitsobrits, Jun 5, 2022
    System is a custom from Hebels in the NL, and is as you surmised:

    Stock F single distributor fitted with two 123 modules mounted 135 deg apart
    Stock F single distributor cap
    Stock F double-ended rotor for single cap

    1-4 bank is using the center connection.

    Swapping parts around this morning to see if/how the problem moves.
     
    Dane likes this.
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,779
    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    #4 Steve Magnusson, Jun 5, 2022
    That actually removes one variable in your search for the trouble -- the "extra" air gap between the rotor and the cap's not-center coil connection is something not helpful for that bank.

    Please let us know if the swapping of components gives a clue -- you may need to do some testing, readjusting, retesting, etc. to get the 135 deg relationship perfect (or send it back to your supplier for the 135 deg adjustment), but, even if not perfect, you should be able to rule the 123 modules in or out. However, better to swap things (that don't need readjustment) first like the coils and/or any separate electronic modules. Is everything contained inside the 123 module itself, or do they plug into something else? Good Hunting!
     
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  5. bitsobrits

    bitsobrits Formula Junior
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    Steve
    #5 bitsobrits, Jun 5, 2022
    Swapped coil leads and trigger wires, and no noticeable change. Got enough #1 firing 'hits' to verify the timing (for the front bank anyway) is close. Hard to say if it's spot on with the cylinder cutting in/out. Put the timing pickup on the other rear cylinders and see the same erratic firing. After lunch I'll check the 5-8 bank timing.

    There are no external modules. The two 123 PCBs are mounted in an alloy cylinder with only the top one visible, so I can't see how they are clocked relative to each other. It seems to me they must be correct or quite near, as when all cylinders fire the engine immediately increases RPM and sounds very smooth.

    It's the erratic and variable nature of the problem that has me thinking the issue maybe with the rotor and/or cap, maybe coils.
     

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