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Converting from Dual to a Single Distributor for US Spec 308

Discussion in '308/328' started by ItalianProjects101, Mar 3, 2024.

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  1. ItalianProjects101

    ItalianProjects101 Karting

    Feb 5, 2023
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    #1 ItalianProjects101, Mar 3, 2024
    Hello,

    I'm currently in the midst of a project to modify my US spec 1978 Ferrari 308, and one of the things I'm considering is converting from two distributors to a single distributor setup. From my understanding, this is possible, and based on my understandings I'll need a single distributor cap and rotor arm and install these on one of my distributors to accomplish this. Am I correct on this?

    I plan to install a Petronix MR-183 in conjunction with this modification. My hope is that this combination will not only simplify the ignition system but also potentially improve performance and reliability.
    [​IMG]
    Before I proceed, I wanted to reach out to this knowledgeable community to confirm whether my understanding is correct. Can I indeed convert from dual distributors to a single distributor on my US spec 308? And would simply swapping out the distributor cap and rotor arm on one of my bodies>

    Furthermore, if anyone has experience with the Petronix MR-183 or similar ignition upgrades, I would greatly appreciate any insights or advice you can offer. I'm aiming to make informed decisions as I continue to enhance and optimize my Ferrari 308.

    Thank you all for your expertise and assistance!
     
  2. bitsobrits

    bitsobrits Formula Junior
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    Nov 12, 2011
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    Omaha, NE area, US
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    Steve
    #2 bitsobrits, Mar 3, 2024
    Last edited: Mar 3, 2024
    I pursued this same goal. Unfortunately it's not as easy as a simple cap and rotor swap, as the rotor mounting method is very different between the 4cyl and 8cyl versions, with the 8cyl unit having a longer shaft with a threaded hole in it. Cap fits fine, though. I spent several months trying to find a reasonably priced 8cyl distributor that wasn't junk. In the end I had a machine shop cut down the rotor shaft in one of my 4 cyl distributors and make up a suitably longer partial rotor shaft which was press fit and pinned into a counterbore of the shortened original shaft. Sent it to Dave North for new bearings and a proper recurve to factory specs, then installed the dual Pertronix triggers that came the car. Works beautifully. With the machine work, recurve and new cap/rotor I spent about $1500, which I deemed not too bad for an as new 8cyl type unit.

    And after all that time and money, I bought a 123+ distributor 8cyl from a guy in the Netherlands which is what I'm running:) I keep the mechanical unit in the trunk as a backup.
     

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  3. flyngti

    flyngti Formula 3

    Jul 16, 2009
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    #3 flyngti, Mar 5, 2024
    I have a Pertronix MR-183 in my 78. Maybe I've just been unlucky, but I've had two pickup units fail. One was DOA on initial install, then another one failed about 10 months later. Then I had a Pertronix Flamethrower fail. Needless to say, I'm not Pertronix fan boy at the moment. On the next failure I'd be tempted to go back to points
     
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  4. mike996

    mike996 F1 Veteran

    Jun 14, 2008
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    Mike 996
    #4 mike996, Mar 5, 2024
    FWIW, currently manufactured points are not nearly as durable as they used to be. I use the OEM points ignition on two motor cycles. They work well and, with the OEM centrifugal advance, actually perform better than the aftermarket EI systems I've had on both bikes. BUT the points don't last very long compared to the "old days." :(
     
  5. miked

    miked Formula Junior

    Feb 7, 2001
    893
    Cincinnati, Ohio
    #5 miked, Mar 5, 2024
    Exactly, I am currently using points on my BSA 650 Spitfire that I have owned 50+ years, today's products don't last nearly as long. Also use them in Wico magnetos but that is a different kettle of fish.

    Many years ago there was a popular mod using a Ford 8 cylinder distributor cap and a machined aluminum adapter ring mounted on the forward distributor (the other distributor being removed) that seemed to be successful. Back in the day I looked at a Nissan (Datsun) pickup truck dual level distributor similar to the single dist. Ferrari cap. It was used for dual plug ignition on their 4 cylinder engine. I bought one at a junkyard to experiment with but even at that time the Datsun cap was nearly NLA.

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