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OT: Magneto Problem?

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  • OT: Magneto Problem?

    Hi All,

    I have an old Fairbanks-Morse Z model stationary engine that was running, but now doesn't. From trouble shooting I found that the Magneto is firing intermittently (mostly not). It is a J1A2 model. I have tried cleaning it up, but that had no effect. Does anyone know where I can get this thing fixed? There aren't a lot of magneto shops in the area any more.

    Do yourself a favor and see if your TV carrier has America One News Network (AONN). 208 on Uverse. It is good old fashion news, unlike the networks, with no hype, bias or other BS.

  • #2
    For one;

    Is it a spark or ignitor ignition?
    Jim H.


    • #3
      Here's another one with a forum just for mag heads.
      Been there, probably broke it, doing that!
      I am not a lawyer, and never played one on TV!
      All the usual and standard disclaimers apply. Do not try this at home, use only as directed, No warranties express or implied, for the intended use or the suggested uses, Wear safety glasses, closed course, professionals only


      • #4

        I have a 7-1/2hp Z,what model is yours?
        I just need one more tool,just one!


        • #5
          Thanks guys,

          That was a quick response.
          It is a spark ignition.
          Mine is a 2 hp model I got about a year ago. It was a non-runner which I cleaned up and repainted. It ran very well last year, but sat up all winter. This week I got it out to get ready to sell and had a devil of a time getting it to run. Oh well, I guess I really didn't want sell it anyway.

          Do yourself a favor and see if your TV carrier has America One News Network (AONN). 208 on Uverse. It is good old fashion news, unlike the networks, with no hype, bias or other BS.


          • #6
            I had an engine with a mag that would have no spark after sitting for long periods, it was corrosion on the points. It would take a lot of filing/sandpapering/whatever to get it to spark reliably. A bit of fooling would get some intermittant sparking, but it took quite a lot of effort to really get 'er done. Once running, if it was operated occassionally, it was fine.

            Maybe more work on the points?


            • #7
              The voltage from a magneto depends on.....

              the current flowing before the points open

              the speed with which the points fully open, i.e. one sharp opening, vs a "scratchy" opening that loses energy.

              not having any leakage paths in the ignition.

              Dirty points affect BOTH the current and the speed of opening, so they are key.

              I always get confused on the "Z" because there is, IIRC, a 'Z"" that is a flywheel open engine, and another "Z" that is an all enclosed throttle-governed version that isn't very interesting.

              I dunno the sub-models, is this throttle governed?

              Keep eye on ball.
              Hashim Khan


              • #8
                The first Z was an open flywheel engine. It is referred to as the "headless" Z as the cylinder and head were cast as one part. The later Z is the "dishpan" engine, it is closed construction with "dishpan" flywheels.

                The magnets will also weaken over time, but just over a season, corrosion is more likely the culprit. Condensation and corruption in the cap will also cause stray currents. Clean and dry everything three or four times and it will probably work eventually.
                Jim H.


                • #9
                  Randy, there are several magneto repair shops around, check Gas Engine Magazine. They advertize in there. Or check out the GEM web site.



                  • #10
                    Clean the points, the setting is .011 to .014 if I remember.. I had one on the harley.. THE wire coming off the magneto? you can pull it loose and see if the fire gets better.. Setting the timing, I'd put the mark up on spot, then set the points and adjust the dist position till I could pull cigarette cellophane out.. *barely open..

                    THE capacitor in there, I put a big mallory one on the outside of my magneto on the bike, put a hacksaw blade on the post there.. push in to short out and ground the magneto to kill the engine.

                    Once in the 70s My coil went out up in Indiana or Ohio, I forget, was Saturday afternoon late, there was this tractor on the side of the road as I pushed down the road looking for somewhere to spend the night, it had the same magneto on it.. I swapped coils with him and left him a $20 under the cap.. I hope he forgave me..

                    Also, the spark plugs didn't gap at .032, seems it was something odd like .017.. or such.. Lottas luck. *(edit to add one more thing??) ok.. if anyone ever hooks 12 volts to the outside post.. the magnets are ruined.. makes the coil into a electromagnet and destroys the armature..

                    I had one on a old wisconsin motor from a mine pump.. same exact setup.. except it had a funky grounded spark plug sheath that bolted to the plug.. never found a replacement plug for it.. I had it n-rigged.. You could take that thing out, wrap a string around the shaft and really crank worms out of the ground.. never got to try it on fish..
                    Last edited by Dawai; 05-09-2009, 11:38 PM.
                    Excuse me, I farted.


                    • #11
                      Thanks Again Guys,

                      That Smokestack website is great. I never knew it existed. I also have an old Allis Chalmers C tractor that is also in project mode. I will be able to waste a lot of time on that site.
                      Here is a picture of the FM engine.

                      Do yourself a favor and see if your TV carrier has America One News Network (AONN). 208 on Uverse. It is good old fashion news, unlike the networks, with no hype, bias or other BS.


                      • #12
                        Yep, that's the "ugly Z", although a nice example of it.

                        good engine, run a lineshaft fine. Not nearly as interesting to me as a hit and miss

                        Keep eye on ball.
                        Hashim Khan


                        • #13
                          That's a model Z, style D. Also know as a "salt block" or "lunch pail" engine. A real b****h to start with the crank FM provided.

                          I've had a couple of those over the years. One was on a old Wheel Horse tractor frame. Used it to get around show grounds. The other was a factory generator set-up. 32 volt DC with a a little radiator on top. Neat little rig. You could use the generator as a starter motor. Kinda wish I never sold those two.
                          No matter where you go, there you are!

                          Hal C.