1960 Evinrude Vacuum cut-out switch

[Grandpa Mike]

I have done my homework and read what "sticky's" I could find re: the cut-out switch. I'm somewhat disappointed that even on a general internet search, I can't find much on old outboard cut-out switch systems and operation.

Ours is a 1960 Evinrude Lark ll, 40 hp. On the port side of the engine is a device that is connected to crankcase pressure/vacuum (by a hose) in addition to a few wires. I did see that there are also connections to what appear to be mercury switches on the throttle linkage. I've figured out that the mercury switches are ensure the engine starts at a reasonable RPM. Their position, angle and connectivity to the throttle linkage makes that pretty obvious.

I have done what can be done, thoroughly....in the full restoration of the power-head and lower drive. Completely overhauled.

We've replaced what appear to be factory hoses, both fuel and water. New points, coils, condensers, plugs and plug wires. The carb was overhauled and kitted by me yesterday. New t-stat & fuel strainer.

What we are doing here is a full restoration right down to the graphics on the engine cover. In the interest of being thorough...I wanted to ensure that everything and anything that might cause a problem was new, repaired or replaced.

Synchronized the manual ignition advance, the whole enchilada. Honestly though, if I've found anything that is specific to marine outboards, I've asked. The cut-out switch is I suppose the last thing.

Can someone point me to a link or provide some info on it's operation and wiring. This thing is certainly not self-evident to an old-crusty auto mechanic like me.

Thanks a bunch! (picture to be attached as soon as I get one)
Mike

 

[nwcove]

Re: 1960 Evinrude Vacuum cut-out switch

http://maxrules.com/graphics/omc/wiring/1957-60_35-40.jpg

( the top secret file at the beginning of this forum is a wonderfull resource)

not 100% sure on the vacuum cut out switch, but from what i understand, it kills spark to one cyl in the event that the motor is over revving .

 

[HighTrim]

Re: 1960 Evinrude Vacuum cut-out switch

Ok crash course.

The vaccuum cutout switch kills 1 cylinder when it detects high vaccuum in the intake manifold (ie over revving the motor)

Now you have 2 mercury switches. They were like this from '58 to '61.

1 of the mercury switches was to prevent starting your motor when the throttle was too far advanced as you figured. The other one is to actually disable the cutout switch at high throttle settings. They needed this since at a cruise throttle setting the vaccuum could be high enough to kill 1 cylinder when not intended, and would give you a miss. The second mercury switch remedied this.

 

[gm280]

Re: 1960 Evinrude Vacuum cut-out switch

Yes nwcove hit the nail on the head with what the cut-out switch does. The theory, at least from the actual Johnson shop manual, states that in the event that you close the throttle butterflies off quickly, or a wide open high vacuum condition as well, that the engine doesn't go into what they call runaway mode being how the vacuum goes instantly very high in that condition. So they placed a vacuum hose to a switch that if the vacuum goes too high, it sucks a diaphragm closed and grounds the spark to one cylinder?s point/coil setup to reduce engine RPMs to keep from that run-away condition. On my OB it is connected to the second cylinder to accomplish that goal. Yours is probably connected in the same fashion too. There should be a wire connected to the center terminal on that switch that goes to the point/coil assembly for one of your points and maybe even another wire to one of the attaching or mounting screws for grounding too. So you can test that switch with a vacuum source and an ohm meter or a light bulb and 12 volt source... Hope that explains it...

 

[Grandpa Mike]

Re: 1960 Evinrude Vacuum cut-out switch

I did read the Top Secret files first, couldn't find what I was looking for which was...exactly what your guys just described. Thanks a million! Great info!

 

[Industrialmaterial]

Re: 1960 Evinrude Vacuum cut-out switch

Hello, I'm doing the same on the same motor. This switch is a mystery to me as well. As well as the last item that I can think of that is keeping me from running. Did you have any luck?

 

[fittyyamaha]

Re: 1960 Evinrude Vacuum cut-out switch

Hello, I'm doing the same on the same motor. This switch is a mystery to me as well. As well as the last item that I can think of that is keeping me from running. Did you have any luck?

If the cutout switch is bad (diaphram leaking) will it make egine cut off after running full throttle 10 minutes$
Post said will cut out one cylinder .My 1975 40hp johnson 40EL75 will cut off after 10min run full throttle
It does not skip or miss at any time. When it shuts off feel like you turn off ignition and is hard to restart
even it you pump fuel bulb and choke.Any help would be appreciated

 

[WIMUSKY]

Re: 1960 Evinrude Vacuum cut-out switch

Industrisalmaterial - This thread is over 90 days old. Please adhere to the red box that was at the bottom of the page before you posted. 90 day old or older threads are to be left to go to the archives... Please start your own thread....... Thank you.....