1964 Johnson 40 hp Ignition System & Airguide Tach Compatability

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  • June 23, 2015 at 9:56 pm #1843
    keb
    Participant

      I own a 1964 Johnson 40hp electric start/shift and recently purchased an Airguide Tachometer (with sending unit) Model 653 assuming it would be compatible based on the following chart from the classic boat work website.

      http://www.classicboatwork.com/classicp … 0Guide.pdf

      However, the instructions for the tach, that i just downloaded (also from the classic boat work site), explicitly state the Airguide model 653 is only for magneto ignitions and will not work with battery ignitions. For magneto ignitions the instructions state the tach is supposed to be connected to the "magneto primary" and for other model designed for battery ignition the tach is connected to the breaker points terminal. I preface my questions with the disclaimer that i know little about outboards except how to do routine maintenance.

      My questions are the following:
      1. What type of ignition do i have?
      2. Although my ignition is battery powered doesn’t it have a magneto?
      3. If i do not have the correct model tach, what Airguide tach models from the chart (see link) is compatible with my particular engine?
      4. If i do have the correct tach, how would I install it?

      I appreciate any help anyone could provide me,

      Ken

      June 23, 2015 at 10:23 pm #18781
      phil-b
      Participant

        I’ve never heard of a 1950’s/1960’s OMC twin that wasn’t magneto ignition, even ones with generators and electric shift..

        I’m pretty sure our 1965 90hp Starflite V-4 was battery ignition tho…..

        June 23, 2015 at 10:24 pm #18782
        Mumbles
        Participant

          Hi Ken,

          1. Your Johnson has a magneto type ignition system.

          2. Your ignition is not battery powered, it is a self contained magneto system. Your electric starter motor used to crank the motor over is powered by the battery. Pulling the motor over manually with a rope will also start the motor in case the battery goes dead.

          3. The way I see it, the chart says you have the correct tach. 😀

          4. Good question. I’m sure somebody else has the answer for that one.

          June 24, 2015 at 6:06 am #18805
          Mumbles
          Participant

            You might need a matching transmitter (signal generator) to get your tach working properly.

            The 653 instructions are available here for $1.79.

            http://www.classicboatwork.com/classicp … truct.html

            June 24, 2015 at 9:38 pm #18847
            keb
            Participant

              Thanks for clearing that up for me guys, very helpful! I did download the instructions for the tach, now i just need to install it!

              June 24, 2015 at 10:25 pm #18850
              keb
              Participant

                I have an additional question, the instruction manual for the Airguide 653 Tach explains i need to connect the tach to the "magneto primary". Can you please explain where this would be. On the engine? or can I connect to the wires that run from the magneto to the ignition system? The following link from iboats has a schematic of the wiring system I am dealing with. The schematic is in post #6 of the discussion.

                http://forums.iboats.com/forum/engine-r … elp-needed

                Again I appreciate the help.

                June 24, 2015 at 11:03 pm #18851
                phil-b
                Participant

                  The two black wires going to your key switch "M" terminals connect to the "primary" side of the magneto coils.
                  Either should do.

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