big twin cutout switch

[pcrussell50]

1959 rds21b 35hp super seahorse

mine runs great, but i am trying to learn as much about it as possible. the cutout switch thing with the vacuum tube on it appears to be bypassed by whoever maintained the motor before i got it. can i just plug the vacuum hose and remove the cutout switch. or is it really better to keep it to prevent a runaway? heck, i don't even know if my cutout switch actually still works?

right now, it's rigged so the way i shut the motor off is by merely pulling the throttle all the way back. that was how the previous maintainer set it up. i have heard that the original way to shut off the motor was that turning off the key grounded one of the coils, [? only one?], and that most people rig it the way it's rigged right now, to shut off the motor by pulling the throttle all the way back.

also there's no mercury "tilt" switch on mine. i'm not too worried about doing without that unless you all think i should find one and rig it up.

-peter

 

[tashasdaddy]

Re: big twin cutout switch

i'm not going to say it is all right, but many run with out it. the 2 black wire coming from the timing plate are the kill wires, grounding them kills the motor.

 

[pcrussell50]

Re: big twin cutout switch

heh, heh...i don't even have the two black wires coming from the timing plate, [i'm not the one who removed them, either]. do they attach on the underside of the plate or the top side of it? IOW, can i re-attach them without removing the timimg plate. and then where do they go? to the cutout switch? then there are two wires that go from the cutout switch to the harness plug? [guessing here. i'm away from my seloc manual till monday].

-peter

 

[CATransplant]

Re: big twin cutout switch

Putting the wires back in will require pulling the flywheel and the timing plate.

Here's the deal: Leaving the vacuum cutout switch disconnected makes you vulnerable to a neutral runaway of the engine. That's why it's there...it happens, and can destroy that engine.

The mercury switch is that engine's way of not allowing the starter to run unless you're in neutral. It's an important safety feature, since starting in gear can easily toss someone overboard. It happens.

Best advice I can give is to restore those safety features to their original condition. You'll do as you please, but remember that you need to remember to put the thing in neutral before starting.

That's a '59, so you have the electric choke. That's the best way to kill that engine if you don't have the kill wires. That way, you can set the idle so the engine doesn't die when you pull the trottle control all the way back.

Think about it. You should be able to find a junk engine around that has those parts, since there were so many of them. It's worth doing.

 

[pcrussell50]

Re: big twin cutout switch

aaah. good words yours are. I'll have to do some heavy ponderng. I've also found a local dealer who's good at finding parts for these old warhorses.

-peter

 

[lindy46]

Re: big twin cutout switch

The kill wires actually connect to the points - one to each set of points. They then run to the key switch - when the key is in the "off" position, they ground the points together, killing the spark. The wire also branches from the lower coil/points to the cut-out switch. No big deal to re-connect them, but you do have to pull the flywheel. You can check your cut-out switch by removing it and putting a vacuum on the hose. The put an ohmeter on the two connectors - a vacuum should close the circuit.

 

[F_R]

Re: big twin cutout switch

Here's the real deal. There are supposed to be two wires coming off the bottom of the armature plate. Each one goes to a set of points. One of the wires goes to the center of the cut-out switch. Another wire from that same center post goes forward to the ignition switch.

The other wire from the points goes directly forward to the ignition switch. Turning the switch to "off" shorts those wires together and kills the ignition.

Now, back to the cut-out switch. It is mounted on plastic, insulating it from ground. A wire goes from one of the switch's corners to a mercury switch on the throttle gears. The mercury switch grounds the cut-out switch housing when the throttle is at a slow setting. At faster settings, the cut-out is ungrounded and inoperative. This feature is important because otherwise the cut-out may operate at certain high speed conditions, causing intermittant loss of spark and misfiring on one cylinder.

The 1958-59 models had a dual mercury switch. One section is for the cut-out switch grounding as just explained. The other section is in series with the starter solenoid to prevent starting the motor at high throttle settings. Newer models had a micro switch instead of mercury switches.

With no cut-out switch and no ignition switch, you are bound to experience runaway sooner or later. It can be a scary experience. If you at least had a stop button or igniton switch, you could turn it off. But as it is, you just have to hope it will slow back down...someday.

 

[pcrussell50]

Re: big twin cutout switch

With no cut-out switch and no ignition switch, you are bound to experience runaway sooner or later. It can be a scary experience. If you at least had a stop button or igniton switch, you could turn it off. But as it is, you just have to hope it will slow back down...someday.

damned scary stuff, that is!

i guess i need to learn more about runaways. can an engine go runaway on you even with the throttle plate closed? how about with the choke closed?

-peter

 

[F_R]

Re: big twin cutout switch

damned scary stuff, that is!

i guess i need to learn more about runaways. can an engine go runaway on you even with the throttle plate closed? how about with the choke closed?

-peter

Absolutely!! That's when it begins.

Actually, it begins when you rev it up above a certain point while in neutral....or break a shear pin. Once it revs beyond that critical point in neutral, it will continue to rev even though the throttle is closed. That's runaway. Choking usually makes it worse.

If you ever look at the throttle plate, you will see big holes in it. It is impossible to completely close it for that reason, and why it does no good.

 

[lindy46]

Re: big twin cutout switch

As long as the plugs are sparking and gas is getting to the cylinders, the motor can continue running.

 

[pcrussell50]

Re: big twin cutout switch

thanks, F_R!

i'm away from my seloc manual till tomorrow, whereupon you all have convinced me to get an ignition switch and the cutout switch up and running, so i want to dissect this a little in case the manual is not clear enough.

lets call the point sets points1 and points2...

Here's the real deal. There are supposed to be two wires coming off the bottom of the armature plate. Each one goes to a set of points. One of the wires goes to the center of the cut-out switch. Another wire from that same center post goes forward to the ignition switch.

points1 should have a wire running from itself to the center of the cutout switch. and then another from the center of the cutout switch to the ignition switch.

F_R sez
The other wire from the points goes directly forward to the ignition switch. Turning the switch to "off" shorts those wires together and kills the ignition.

points2 has a wire running from itself straight to the ignition switch, [bypassing the cutout switch altogether].

so now then, touching the wires from points1 and points2 together will ground them and kill the ignition. this can be accomplished two different ways:
1] with the ignition switch on the dash
or
2]when vacuum is applied to the cutout switch

however, doesn't the vacuum switch only ground one of them? points1, in our example above? seems i recall this from another post. and the engine _could_ theoretically still run on one cylinder. can i ASSume that in a runaway, the cutout switch killing one cylinder will at least bring it under control?

-peter

 

[lindy46]

Re: big twin cutout switch

The cutout switch grounds the bottom cylinder only, but theoretically killing spark to one cylinder is enough to stop a runaway. Sounds like you've got a good handle on it now. By the way, you should be able to get by with just pulling the flywheel as the bottom of the plate will have holes already drilled through them for the wires. On my '57 I was able to maneuver the wires through the holes without removing the plate.

 

[F_R]

Re: big twin cutout switch

pcrussell, you've got it figured out. The vacuum switch only grounds one cylinder. That is enough to slow it down to safe range, then the cylinder starts firing again. You have to pay attention to know it is even working.

 

[pcrussell50]

Re: big twin cutout switch

just to follow up, went ahead and pulled the flywheel and reconnected the grounding wires to the point sets, in the manner you guys described, then i put it all back together and fired her up. and good news:

1] she fired right up and ran, so i didn't accidentally leave one of them grounded, and the old wiring didn't seek ground by going through the insulation...yet...i'm taking her out for sea trials here in a bit
and
2] i wired a waterproof toggle switch to the dash, and as soon as i threw the switch it shut 'er down, just like it should.

so far, so good

-peter