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How do you set Dual Distributors?

Discussion in 'Technical Q&A' started by zompster, Aug 24, 2004.

  1. zompster

    zompster Rookie

    Aug 24, 2004
    3
    I have a 1976 308 gt/4 with dual marelli distributors. I just removed both distributors to set points in them and forgot to mark the locations of the rotors, and the splined rotary shaft moved,..oops!!
    Is there a shortcut on setting these up the proper way.
     
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  3. tbakowsky

    tbakowsky F1 World Champ
    Professional Ferrari Technician Consultant

    Sep 18, 2002
    15,118
    The Cold North
    Full Name:
    Tom
    Set rear bank to number one cylinder in firing position TDC. Line rotor up with the mark on the distributor case and install. Set front bank to number 5 firing at TDC. Line up rotor with the mark on the distrubutor case and install. This should get you close enough to be able to start and run the car. Then set timing.
     
  4. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,284
    Texas
    Full Name:
    Steve Magnusson
    This thread:

    http://ferrarichat.com/forum/showthread.php?t=6838&highlight=308+Distributor+mark

    has a great picture of the "mark" on the distributor rim mentioned in Tom B.'s instructions.

    #5 fires 90 degrees of crankshaft rotation after #1, so once you've got things figured out and installed for #1, just rotate the crankshaft another 90 degrees (in the normal running direction -- CW as viewed from the crank snout end IIRC) to the PM5-8 mark and that's the #5 firing position (you can't get a peek at the #5 valves like you can with #1).
     
  5. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    10,194
    San Carlos, CA
    Full Name:
    Mitchell Le
    You should also static time it after you install it. Post what kind of ignition you have (1 or 2 points) and timing desired and we'll show you how.
     
  6. zompster

    zompster Rookie

    Aug 24, 2004
    3
    Dual point distributors.

    The old mechanic who was working on my dad's cars was a hack. He has since retired (thank God).
    He had one distributor set correctly and the other is off by 45 degrees. The car actually ran but sputtered and backfired badly.
     
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  8. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    10,194
    San Carlos, CA
    Full Name:
    Mitchell Le
    OK

    1. install the 1-4 dizzy as instructed above to get close
    2. Set the flywheel position to the timing position where you want the car to idle, I think it is a few degrees retarded. You can see the marking on the flywheel.
    3. Retard the dizzy as far as you can, by turning it counter clockwise
    4. Connect a DVM to read ohms across the coil wire and the number 1 spark plug wires. it shoud read infinte resistance.
    5. Slowly turn the dizzy in the clockwise (advance) direction until the DVM meter just shows some resistance. Stop and tighten the dizzy nut.

    Repeat for the other bank.

    It should fire right up after that and reqire very minor adjustments.
     

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