1948 Evinrude Light Four with no spark…need advice

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  • January 8, 2016 at 3:53 pm #29822
    jeff-register
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      US Member

      Tubs,

      What are the Uf rating? Looks like a great fix if they match Uf. I will stop by napa with my meter to measure the capacitance of them later today.
      We need to find out first what capacitance cap is required. I will dig in my mercotronic book & service manual to get an correct rating. Very important to get the correct capacitance. Some guys tune their coils using different caps & measuring output for spectactular spark improvement. Again need a scope & hi volt probe to test. Never have done it yet but have the tools to do it for my KG7 to improve the bendix coils output. Fun testing for me as I enjoy sparky stuff. Its in the web site I sent you on Mags.

      January 8, 2016 at 5:47 pm #29827
      jeff-register
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        US Member

        The photo of your mag is for a Zepher motor. The light four is from 1934 to 1951 serial numbers 4042, 4111, 4178, 4231, 4271, 4315, 4383, & 4389 models. Does that match your motor? Coils 276039 run on 1.5 to 2 amperes, again need a Mercotronic to check. Caps show anywhere from .1 to .4 mfd to be correct. Need your serial number to ID. Float level is 3/4" plugs are chm5-J & set at .25, points are .20, That is all the data my book shows, I’m sorry. GARRY!!!! WE need your help here PLEASE!!
        NEED your serial number to ID please. I show very little on the 4 cylinder mags I thought my book had more as it goes back further than the light four 9.7hp motor.

        January 8, 2016 at 6:12 pm #29829
        jeff-register
        Participant

          US Member

          PS. You only need one wire each from each coil going to the bottom. Points wire goes to the caps so only one wire is required. Can pick up ground under the cap screws to help with the rats nest of wire. The coils run either the top or bottom cylinders. To find out which one set the points & rotate until the points start to open. Now stick a screwdriver in the plug hole to find which top or bottom cylinders have the pistons close to the top of the bore, simple! The pistons that are on top go to that set of points & coil.

          January 9, 2016 at 3:04 am #29863
          huntleybill
          Participant

            US Member

            Thank you Tubs. I will try them.

            January 9, 2016 at 3:09 am #29864
            huntleybill
            Participant

              US Member

              The model number on mine is 4389

              January 9, 2016 at 5:13 am #29871
              garry-in-michigan
              Participant

                Lifetime Member

                Model 4389 was built after the second World War and has alnico magnets in the flywheel. It doesn’t need recharging and is dependable as long as it is kept clean. The Zephyr uses the same coils, points and condensers. The condensers (capacitors) are the iffy part of the assembly.

                January 9, 2016 at 2:40 pm #29883
                jeff-register
                Participant

                  US Member

                  Garry,
                  Thank you for your advice! He is sending me his caps to check them with the Mercotronic. Do you have the specs of what mfd the caps should be in your books? I can’t find much in my Evinrude service book. He is lucky the coils are still good.
                  Thank you for all your expert advice, You are a gold mine of knowledge! My Evinrude manual shows the magneto plate or flat to be for a Zephyr not a light 4 . Was the plate the same as the Zephyr too? Should we replace the top seal for the crankshaft too?
                  Jeff

                  January 9, 2016 at 4:35 pm #29893
                  Tubs
                  Participant

                    A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

                    • This reply was modified 6 years, 9 months ago by Tubs.
                    • This reply was modified 4 years, 5 months ago by Tubs.
                    January 9, 2016 at 6:10 pm #29897
                    Mumbles
                    Participant

                      4389 uses 0.20 uF condensers (capacitors) in the ignition system. The NLA originals have extra long leads on them and if they are bad, they can be replaced with modern Vishay or Orange Drop caps. The pre-war Zephyrs and Lightfours have a different uF rating as the coils are slightly different than the later ones.

                      January 10, 2016 at 2:24 am #29921
                      jeff-register
                      Participant

                        US Member

                        Thanks so much. He is sending me his caps to test on the mercotronic for leakage & capacitance as well. Now I know what to expect for test readings, Time to copy that chart!! Where did it come from anyway?
                        Thanks much,
                        Jeff

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