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Hi all, I have recently worked on restoring a 50’s wood kit boat. I have this motor, but of course no one will work on it. I’ve put a starter on it, checked compression, now am wiring it – the external harness is missing. I’m pretty close to finished, but this on part on the left side of the engine has a wire that goes to the external connector, plus up to the top of the motor, and a fuel hose on it. What is the part and what do I connect it to externally?
Thanks in advance, Don
That is the vacuum cut out switch…These engines have a tendency to “run away” when reduced quickly to idle in neutral. That switch is vacuum controlled and connected to one crankcase, so spark to that cylinder is cut out when excessive vacuum is sensed on that crankcase (high RPM with throttle valve closed). Needless to say, there are other switches involved that cancel this feature out when the throttle is set at higher settings. The engine will run fine without that feature being wired up, but it won’t have any “runaway protection”. You won’t be able to shut they engine off either. I sure hope you find the correct wiring harness for this engine!
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That thing baffles most everybody. So here goes—
Those motors may run wild (runaway) if revved up in neutral or other no-load conditions, such as a broken shear pin. That item in question is a vacuum cut-out switch that will slow the motor down if it senses a high vacuum in the intake manifold (runaway) condition.
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Thanks for all of that, I wondered what the other little oval things were – they are the mercury switches! I don’t have an ignition switch, just the start and choke switches. So does the wire go to the start switch or the battery? Or the starter solenoid? But my starter solenoid only has 3 poles, not 4. I’m guessing wire to the battery because it always needs 12v to work?
One more, sorry to wear you guys out, there is a wire from the control harness to the to of the engine, I assume the magnetos? The diagram shows it going to a pole on the starter solenoid, but my solenoid doesn’t have that. Does it go on the pole from the starter switch or the ground pole on the bottom? I’m thinking ground because the connection in the engine is not insulated.
Thanks again, Don
So now we are left wondering if that is an old 6 Volt solenoid. Or grounded base or insulated base solenoid? Sorry, I’ll let somebody else re-engineer it for you, if they want to mess with it.
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