1957 Evinrude big twin

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  • August 19, 2024 at 9:29 am #289951
    labrador-guy
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      US Member

      Could someone enlighten me as to what these two wires are for?  They are attached to the throttle control gears on the port side of the engine,  both go to ground.  Can they be eliminated?   Without fear of mental disorder!

      dale

      August 19, 2024 at 9:39 am #289953
      joecb
      Participant

        US Member

        Hi ya’  … my 57  Evinrude Lark (the one that likes to run on one cylinder)  has a small mercury switch in that area that acts to prevent starter motor operation when the throttle is advanced too far.  Perhaps someone has remover the switch and the wires remain

        Joe B

         

        August 19, 2024 at 12:14 pm #289956
        frankr
        Participant

          US Member

          The mercury switch is clearly there in the picture.  But the wire appears to be burnt off from it.  The wire is supposed to be welded to the little pin sticking out of the mercury switch.  Welded because the pin is stainless steel and unsolderable.  It is very common to see the wire burnt off like that.  It happens almost instantly from improper attempts at troubleshooting or jump starting.

          Bottom line is it can no longer function as it is now.   In other words, its purpose is to prevent electric starter operation at high throttle settings, and if the starter is working, the system has been defeated somehow.

          BTW, excellent picture.

          1 user thanked author for this post.
          The Boat House
          August 19, 2024 at 9:38 pm #289973
          labrador-guy
          Participant

            US Member

            I hauled my VOM out to the shed and sure enough that switch at low speed setting has continuity and at high speed no continuity.   It might be a good idea to run my starter solenoid through that switch.  I am putting electric start on this motor.  It did not have electric start so how could the switch work with both wires going to ground.   Neither wire was hooked to the points.  Life is a mystery!

            thanks dale

            August 19, 2024 at 11:10 pm #289974
            Buccaneer
            Participant

              US Member

              Dale, does that motor have a vacuum “cut out” switch to kill one
              cylinder if the engine “runs away”? The Mercury switch may
              be part of the ground circuit for the vacuum switch, and for
              disabling starting when the throttle is set too fast.
              Seems like some motors had two mercury switches??

              Prepare to be boarded!

              August 20, 2024 at 12:41 am #289975
              frankr
              Participant

                US Member

                When you turn the key to the start position (or push the start button), 12V is sent to one of the small terminals on this starter solenoid. From there it goes through the pull-in”coil within the solenoid and out through this other small solenoid terminal. But nothing happens yet because the it has not reached ground and there is no current flow. through the pull-in coil.

                So, going on from there it is presented to the pin on the mercury switch.. The mercury switch is a little metal bottle with a cork in one end and the pin sticking through the cork. There is a drop of liquid mercury in this bottle. When the bottle is tilted one way the drop of mercury runs back into the bottle and nothing happens.. But tilt it the other way and the drop of mercury runs back to the corked end and connects the the pin to the metal shell of the bottle.. This connects the bottle to its mounting tab grounding it to the motor and current flows and the pull-in coil becomes magnetic and closes the heavy duty contacts to run the starter.

                The other wire merely ensures a good solid connection between the mounting tab and the restating throttle gear.

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