328 Can anyone shed light on setting Distributor Rotor Phasing? | FerrariChat
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328 Can anyone shed light on setting Distributor Rotor Phasing?

Discussion in '308/328' started by Jerry458, Apr 5, 2025.

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  1. Jerry458

    Jerry458 Karting

    Nov 6, 2024
    93
    NYC
    #1 Jerry458, Apr 5, 2025
    On my 86 328 I recently did new plugs, wires, distributor caps, rotors etc and the engine seems slightly out of time and backfires under throttle input. it starts up and runs but not as smooth as it should. All wires are good connections and everything seems ok except I think the rotors are not in the right spot.

    on the 308 the distributor rotors snap in only one direction so you cant really mess this up but on the 328 they can actually be oriented in 3 positions as shown and this for sure will affect timing.
    I can not find any info on this in the digital shop manual how to set and check rotor phasing as this might be the issue now. If anyone has a thread or info please share in this thread.

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  2. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    #2 Rifledriver, Apr 5, 2025
    The indexing pin and the water dain hole both point down.
     
  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #3 Steve Magnusson, Apr 5, 2025
    Last edited: Apr 5, 2025
    I don't think so -- the mounting holes of the 126139 dist rotor are not equally-spaced so the rotor only goes on in one position. Your symptom sounds a lot more like you got a spark plug wire in the wrong place -- have you checked the firing order of the wires in the caps?
     
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  4. Freddie328

    Freddie328 Formula Junior

    Jul 29, 2013
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    Richard
    #4 Freddie328, Apr 6, 2025
    With the timing marks set at No 1 cylinder TDC, the rotor position is this...
    But I think Steve's response is more likely to be the issue.
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  5. Jerry458

    Jerry458 Karting

    Nov 6, 2024
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    #5 Jerry458, Apr 6, 2025
    there is no index pin on this camshaft end on both banks on this car this is why it can be installed in 3 positions easily. I will post a photo late with the rotor removed
     
  6. Jerry458

    Jerry458 Karting

    Nov 6, 2024
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    #6 Jerry458, Apr 6, 2025
    wires all all in the correct locations but if you see the end plate off the cam it is triangular and I actually was able to mount the rotor in 3 different positions and once I verified this I decided to post this thread asking about this.There is no locating pin coming off the cam end or in the rotor to index location. I am going to post a photo of the end plate with the rotor removed so you guys can see as it is totally different than the photo posted in the thread by Freddie328
     
  7. Jerry458

    Jerry458 Karting

    Nov 6, 2024
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    #7 Jerry458, Apr 6, 2025
    your end plate mount is different than mine what year is you car and do you have a reference photo of the other bank with the rotor orientation at Cyl 1 TDC
     
  8. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #8 Steve Magnusson, Apr 6, 2025
    Last edited: Apr 6, 2025
    Then you either somehow managed to jam the three mounting screws in, or didn't use all three mounting screws (I believe the two triangular outline shapes should match each other) -- good luck!
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  9. Freddie328

    Freddie328 Formula Junior

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    #9 Freddie328, Apr 6, 2025
    Mine's an October 88 build.
    I don't have a pic of the left hand cylinder rotor position. But it should be pointing in the same direction as the right hand cylinder, when No1 cylinder timing marks are set to TDC.
     
  10. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #10 Rifledriver, Apr 6, 2025
    The end of the cam does not have a water drain hole either but the distributor base plate has both.
    The rotor and the base plate both have bolt patterns that allow for a single mounting position only. It was designed to be idiot proof.
     
  11. yelcab

    yelcab F1 World Champ
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    Nov 29, 2001
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    #11 yelcab, Apr 7, 2025
    Jerry, slow down, back out of the work and do it again.

    1. Distributor mounting plate fits with index pin down.
    2. There is only one way to fit the rotor so all three 7mm bolts can fit.
    3. There are a dozen ways for you to get the ignition wires wrong. Go back to firing order to sort it out.

    Good luck.
     
  12. Jerry458

    Jerry458 Karting

    Nov 6, 2024
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    #12 Jerry458, Apr 7, 2025
    today I actually did try to see if can get all 3 of those 7mm screws with the rotor oriented several ways and you guys were correct it can only screw on one particular way. When I removed the screws and saw how the triangular profile matched the end plate in several directions I assumed it can mount in 3 positions so this is now sorted and verified.

    I think the spark plug wire extenders might be the issue I just ordered new ones the ones that came on this car are red and the car had these horrible yellow Accel wires when i got it . I bought the full ignition kit from AW with the correct wires and and parts but omitted the plug extenders as they looked ok but then again i do not know their age. new plug extenders are OTW in a few days and will redo the wire terminations at the spark plug ends to see if the erratic running improves.
     

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