1941 Johnson KS-15 coil swap

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  • Buccaneer

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 7421
    Topics: 1068
    #284867

    I never got and sage advice on my last query regarding this
    coil swap, so thought I’d just forge ahead, and “wing it”.

    The original K coil lamination would almost fit  an OMC coil
    with little effort, but, there’s no good way to orient the coil
    where there wouldn’t be clearance issues with the flywheel,
    or other.

    DSCN9046

    DSCN9048

    I have a couple of Tecumseh small engine coils I purchased
    in the past for a possibility on a different magneto coil swap,
    which didn’t work out, but “maybe” will on this one.

    In this orientation, the flywheel hub would likely rub.

    DSCN9050

    This orientation looks “doable”.  I checked the height,
    and it looks like there would be enough clearance so
    that the flywheel would not rub.
    I started machining down the width of the lamination
    to fit, but I still have to remove some laminations
    on the height so the coil will slide on.

    The only “issue” that may dampen my hopes and dreams,
    is that the plug wire on this Tecumseh coil is too short,
    and it seems to be “glued in” place. Hopefully the
    coil is still useable after I get the plug wire out.

    Plan “C”, would be a Military surplus Bendix Scintilla
    coil, which would fit fine, but I dread removing those
    coil laminates.

    DSCN9051

    Prepare to be boarded!


    stanley

    US Member - 2 Years
    Replies: 613
    Topics: 114
    #284876

    Why not try an “inconspicuous “splice of the plug wire on the Tecumseh coil ?I’ve spliced plug wires before with good results.


    The Boat House


    Replies: 4516
    Topics: 110
    #284877



    Cut off the shield and solder on the
    wires like the coils you’re taking out.
    I usually add a coat or 2 of liquid tape.
    Tubs
    .


    stanley

    US Member - 2 Years
    Replies: 613
    Topics: 114
    #284878

    And I’ve done a couple like Tubs shows.


    Buccaneer

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 7421
    Topics: 1068
    #284879

    I wished you guys told me this after my first post, lol.
    Too late now, I’ve already machined down the first
    laminate to fit the Tecumseh coil.
    After I get that buttoned up, I’ll check for spark,
    and then decide if I’ll convert the other bad coil,
    or use an original coil that I just happened to pick up
    at Tomahawk last year.

    Prepare to be boarded!


    stanley

    US Member - 2 Years
    Replies: 613
    Topics: 114
    #284880

    For future reference,some of the newer black OMC coils are enough smaller that they will fit where the older thicker green coated coils won’t.I replaced the coil on an OMC foldlight with two of those coils on the original laminates.The length was the issue in that case but those coils would just fit when nothing else would.


    Buccaneer

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 7421
    Topics: 1068
    #284881

    Good to know Stanley. I have a couple of Zongfung coils
    on standby. Maybe I’ll measure the diameter compared to
    the old blue OMC coil, for future reference.
    When I went back out to the garage, I slid that blue omc
    coil on the lam (even though it’s now too small) to eye up
    the height. It probably would have clearance, if prepped
    like the coil in Tubs photo, with the plug wire soldered on
    off the side of the tower.

    Prepare to be boarded!


    Buccaneer

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 7421
    Topics: 1068
    #284883

    Will see if I have better luck posting photos today, but it was nice
    to see my Flambeau again anyway. (Sarcasm!)

    I finished up swapping out one of the original coils for the Tecumseh,
    and tested it out. It’s not the fattest spark I’ve ever seen, but perhaps
    okay?

    I’m debating weather or not to do the same coil swap with the
    other original “bad” coil, or put the one good original on it that
    I had stashed.
    Either way, there’s a few road blocks before this KA-37 may ever
    run again. I lost the stationary half of the point set somehow,
    and the moveable half has a broken “spring steel” spring broken.
    Bigger problem is that I’m awaiting different piston rings, as
    the Maytag rings I installed aren’t going to work out.

    VIDEO…….

    https://youtu.be/s5BonKASWY0

    Comparing the OMC vs. the Tecumseh coil as far as “height”.

    DSCN9054

    The Tecumseh coil all hooked up and ready for a test.
    P.S.- That’s the style of point set I need for the other side,
    in case anyone had one to sell.

    DSCN9055

    I used a .22 mdf capacitor, but not idea what the Tecumseh coil desires.

    DSCN9056

    Prepare to be boarded!


    Tim

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 97
    Topics: 13
    #284890

    Regarding Plan C:

    Military Surplus laminate removal.

    Received  MS coil today and successfully removed the laminates in just under 2 hours without loss of blood, appendages or disparaging words, a win in my cave.  After spinning my prop for 90 minutes I took this approach.

    1. Using a die grinder cut off laminates on both side up close to the coil.
    2. Cleaned up lam ends on bench  grinder
    3. Center drilled lams on drill press using 9/32 bit stopping 1/4 inch short of going all the way through.
    4. Using round flat punch & small hammer drove center lams out opp end.
    5. Separated remaining lams using hammer, straight pick tool, flat blade screwdriver and needle nose pliers.

    Almost want to do this again and clock the time….damn only ordered one coil.

     

     

     

     

     

     

     


    Buccaneer

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 7421
    Topics: 1068
    #284893

    Tim, I believe it was the last Military coil I used that I did
    the same procedure, and kept thinking that there had
    to be an easier way!
    Glad you suceeded!

    Prepare to be boarded!

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