Testing coils, per1938 Bendix Scintilla procedure

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  • Buccaneer

    US Member - 1 Year (includes $3 online payment fee)
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    #283082

    I’d like to test the Bendix TMD coils per the 1938 shop manual.
    The diagram says to use a “Standard Ford Coil”, and to “short out”
    the secondary.
    Do you suppose they’re talking about a Ford Model T coil, or 
    a standard automotive 6v Ford coil per 1938?

    What is the resulting difference if one runs the 6V directly to the Bendix
    coil’s primary, or go thru a Ford coil’s primary first, then to the Bendix
    coil’s primary?

    I have a Model T Ford buzz coil set up with 6v game camera batteries,
    I’ve used to run RBM outboards, that I could use, if that will work.

    I made a new “air gap” tester that will work on my Bendix twin’s two coil system.
    The Bendix coils primary’s are wired in series, and it’s a twin opposed motor,
    hence both plugs fire at once.

    Thoughts? Thanks.

    Coil-Test

    DSCN8710

    DSCN8716

    DSCN8717

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    joecb

    US Member - 2 Years
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    #283089

    I would think that by 1938 it would be a standard Ford 6 V coil, not the model T buzz coil.  Looks like what is going on here is using the Ford coil primary voltage spike to juice the Bendix coil. Normaly one would just use low voltage  ( 6 maybe 12 V) to test a coil, but the voltage from the shorted Ford coil will be considerably higher, like a couple hundred volts… ( I think ?)  We need Jeff R to chime in on this.

    Joe B


    The Boat House


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    #283091



    I’m wondering if not using a 6 volt car battery and
    substituting the needles will produce the same results?
    Looking forward to hearing what you experienced
    with your testing.
    Tubs


    Tom

    US Member - 1 Year (includes $3 online payment fee)
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    #283092

    While the dates don’t match up, I think they DO mean a Model T Coil.  Using the primary side of a Model T coil would generate the same thing as using a Merc-O-Tronic or a Stevens tester with a vibrator tube.  I’ve done this with a Model T coil and one of the dual output military coils to run opposed twins with no magneto.

    If you put the Bendix primary wires in series with the battery and the top and bottom terminals of a Model T coil, you should be generating a spark in the Bendix secondary.  You would have to put the Bendix high tension wires near each other to see the spark.

    Tom


    seakaye12

    US Member - 1 Year (includes $3 online payment fee)
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    #283093

    Buc…is that from a Bendix Manual for outboard repair?  Is it available as a PDF somewhere?


    joecb

    US Member - 2 Years
    Replies: 889
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    #283097

    I think Tom is correct. The Model T coil has the “vibrating” points – the make and break function on the primary circuit that’s needed to fire the test coil

    Joe B


    Buccaneer

    US Member - 1 Year (includes $3 online payment fee)
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    #283098

    I would think that by 1938 it would be a standard Ford 6 V coil, not the model T buzz coil.  Looks like what is going on here is using the Ford coil primary voltage spike to juice the Bendix coil. Normaly one would just use low voltage  ( 6 maybe 12 V) to test a coil, but the voltage from the shorted Ford coil will be considerably higher, like a couple hundred volts… ( I think ?)  We need Jeff R to chime in on this.

    Joe B

    Joe, if one used a regular 6 volt battery, and omitted the
    extra coil, or Ford buzz box, one would have to operate
    the points manually to get a spark perhaps????

    Maybe using the Ford T coil with the vibrating points
    is why the diagram shows it working with the points
    isolated??

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    Buccaneer

    US Member - 1 Year (includes $3 online payment fee)
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    #283099



    I’m wondering if not using a 6 volt car battery and
    substituting the needles will produce the same results?
    Looking forward to hearing what you experienced
    with your testing.
    Tubs

    Hopefully I don’t report back “Disaster”, as those
    coils would be few and far between, and not
    easy to swap out.

     

     

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    Buccaneer

    US Member - 1 Year (includes $3 online payment fee)
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    Topics: 1068
    #283100

    While the dates don’t match up, I think they DO mean a Model T Coil.  Using the primary side of a Model T coil would generate the same thing as using a Merc-O-Tronic or a Stevens tester with a vibrator tube.  I’ve done this with a Model T coil and one of the dual output military coils to run opposed twins with no magneto.

    If you put the Bendix primary wires in series with the battery and the top and bottom terminals of a Model T coil, you should be generating a spark in the Bendix secondary.  You would have to put the Bendix high tension wires near each other to see the spark.

    Tom

    Your theory sounds very plausible to me.
    One would think that it would be safe for the Bendix coils
    if it’s a procedure in the Bendix shop manual.
    Thanks.

    Prepare to be boarded!


    Buccaneer

    US Member - 1 Year (includes $3 online payment fee)
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    Topics: 1068
    #283101

    Buc…is that from a Bendix Manual for outboard repair?  Is it available as a PDF somewhere?

    Yes, it’s an official Bendix manual for repairmen.
    I have it in four separate pdf’s, all but one too large of a file
    to post here.
    I found it online a few years ago…….. not sure if it’s still “out there”.

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