Kill Switch for a ’57 Merc Mark 25

[wabittle]

Hello. Can you use a 2 wire kill switch on a Merc Mark 25 2 cyl by attaching one wire to the points for cyl 1 and the other wire to the points for cyl 2? Seems like one point set or the other must be closed at all crank positions where shorting the two together would effectively disable the spark to both cylinders. Just wondered if this was an acceptable way or if this method has some warts? Thank you

Regards,

Wade

[dave-bernard]

YES !

[Finn Freeman]

This is exactly how OMC did it for their 2 cylinders from ~1957 and
onward. Before that omc said to choke the engine to stop it. Not that
great for starting again afterward because it pretty much floods the engine.
If you waited long enough the engine would probably drain all of the
flooded gas into the lake.

[crosbyman]

see omc diagram

Joining AOMCI has priviledges 🙂

[frankr]

Wade, that is how it’s done.  However, your theory of how it works is only partially correct.  It is true that the closed set of points on the inactive cylinder provides a ground return.  But what you are mossing is that that closed set of points is paralleled by the primary winding of its related coil.  So the coil winding is also a ground return.  True, there is around an Ohm of resistance through that winding, but it still is an adequate ground to kill the active cylinder.

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