Universal mag help please.

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  • bill-mcnamara

    Canada Member - 1 Year (includes $3 online payment fee)
    Replies: 241
    Topics: 58
    #227730

    I rebuilt a mag today for a FD-11.
    When I reinstalled it onto the collar of the engine it seemed to fit a bit loosely.
    Although I’ve rebuilt a few dozen of these mags as part of the hobby, I don’t remember feeling this looseness before. The plate seems to wobble a little on the collar. I can feel a slight side to side movement also.

    I did some measurements with a caliper, and it seems like the gap is about 0.003. Is this within specs?
    I swapped in a second mag plate with similar measurements onto the engine, and it felt snugger.

    I guess a solution would be to disassemble the completed mag and transfer the components to the 2nd base?

    I’ll try to submit a picture that shows the measurements.The 2 engine collars measure in at 1.685″

    Each plate shows 2 measurements, the top one is the diameter measurement of the upper part of the bearing, lower measurement is the bottom of the bearing.

    BTW, the essence of the project is to install electric starting to the gently used motor on the left of the picture. The motor on the right is an original FDE-11, an incomplete parts motor that was gifted to me by friends owning a local repair shop.
    The motor has been well picked over, but provided the starter bracket, functioning starter, electric choke,and lower pan. Well worth the 2 mile drive to pic it up!

    Basically the behavior doesn’t seem to jive with the measurements.

    Any ideas?

    DSCN1219

    • This topic was modified 3 years, 2 months ago by Mumbles.

    crosbyman

    Canada Member - 2 Years
    Replies: 3588
    Topics: 326
    #227742

    retaining ring plate under the armature support seems to have a wider gap.. ?? . is the left picture’s retaining ring flat side up or taper side up ? should be flat side up like the one on the right side

    Joining AOMCI has priviledges 🙂


    fleetwin

    US Member - 2 Years
    Replies: 4737
    Topics: 46
    #227743

    Does the plate have up/down slop as well as the side to side wobble? I’m not sure I understand the two measurements on the mag plates, but the one on the right seems to have a .009″ difference, which is quite a bit. Like Crosby says, make sure the aluminum threaded retainer is oriented properly, flat side up. Wear in the brass ring, and aluminum retainer, will cause up and down slop.
    I don’t know what the measurement of the crankcase pilot bushing is supposed to be, but both blocks seem to measure the same, so I’m guessing there isn’t much wear. Some of us cheat a bit by “dimpling” the brass ring ever so slightly in an effort to minimize slop. Again, the word is “gently”, you don’t want to jam the mag plate or cause it to be stiff when rotating…


    bill-mcnamara

    Canada Member - 1 Year (includes $3 online payment fee)
    Replies: 241
    Topics: 58
    #227762

    Crosbyman,
    Thanks so much, and good eye too!
    That was indeed the problem, fixed in short order.
    I had been under the ring for oil clean-up, as the crank seal had failed and top of engine was oily.

    Surely am glad I asked the experts !

    Bill.


    bill-mcnamara

    Canada Member - 1 Year (includes $3 online payment fee)
    Replies: 241
    Topics: 58
    #227766

    Fleetwin,
    Thanks for your reply and keen eye as well.
    To answer your questions:
    1) The two numbers on both motors represent the top & bottom dimension of the bronze bushing. I was looking for any major taper going on. The top number on the right is actually 1.688″, so differences were only 0.003″ each.
    2) No up and down slop.

    Thanks also for your dimpling trick, it may come in handy some day to take up excessive wear.

    Turns out that only thing suffering from excessive wear was my Brain!


    crosbyman

    Canada Member - 2 Years
    Replies: 3588
    Topics: 326
    #227784

    I am no expert…. I asked the same question/issue recently about my own retaining ring and yours looked upside down 🙂

    (F.R. as always, helped out to fill my voids and kept the crows out of my plate. )

    I am just glad it helped you out

    Patience brings joy….

    Joining AOMCI has priviledges 🙂

    • This reply was modified 3 years, 2 months ago by crosbyman.
    • This reply was modified 3 years, 2 months ago by crosbyman.

    Mumbles


    Replies: 5764
    Topics: 298
    #227845

    If you can wiggle the edge of the mag plate up and down much it means the aluminum boss on the motor or the brass bushing in the mag plate are worn. This allows sideways motion of the plate which affects the points gap which in turn affects the ignition timing.

    To fix this, I remove the brass retaining ring and using a sharp center punch, I lightly punch the aluminum boss in six or eight evenly spaced vertical lines around it. This expands the aluminum enough to eliminate the slop. If the mag plate is too tight after doing this, the dimples can be lightly filed down for clearance. It’s kind of a band-aid fix but it does work.

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