Big Twin 40 safety switch wiring question

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WetWillie
Posts: 96
Joined: Fri Jul 22, 2016 2:59 pm

Big Twin 40 safety switch wiring question

Postby WetWillie » Mon Apr 16, 2018 9:50 pm

I'm trying to connect the wires on my '64 Evinrude Big Twin 40 to a control box that was used on my '56 Evinrude 30. There are 2 white wires coming off a component mounted on the side of the motor. One wire connects to the safety switch under the flywheel. The shop manual diagram shows the other wire connecting to the same terminal on the starter solenoid as the + battery cable. My questions are: can I avoid running the wire to the transom mounted solenoid by connecting it to the + terminal on the starter? And, what function does that wire serve if its providing power to the safety switch when there doesn't appear to be any other wire attached to that switch? Fwiw, The component that the 2 white wires attach to also has a center terminal with 2 wires connected. Both of those wires are black with one going to the - battery terminal and the other to the points.
I have 2 hopes as I type this. One is that the reader will understand my questions and the other is that they'll respond.
THANKS!
Wet Willie

FrankR
Posts: 3154
Joined: Tue Mar 10, 2015 6:32 pm
Location: Florida

Re: Big Twin 40 safety switch wiring question

Postby FrankR » Tue Apr 17, 2018 7:53 am

That is all wrong.
One white wire goes to the safety switch.
Other white wire goes to one of the small terminals on the start solenoid.
The other small terminal on the start solenoid goes to the "S" terminal on the key switch.
You must have the correct solenoid for this to work. A car solenoid won't get it. In fact, a car solenoid will destroy the safety switch.

One of the black wires on the center post of the vacuum switch goes to the points.
Another black wire goes from that same center post to one of the "M" terminals on the key switch.
The other "M" terminal on the key switch goes to the other set of points.
The two "M" terminals function as a kill switch to stop the motor when switch is turned off.

WetWillie
Posts: 96
Joined: Fri Jul 22, 2016 2:59 pm

Re: Big Twin 40 safety switch wiring question

Postby WetWillie » Tue Apr 17, 2018 9:29 am

Thanks Frank. I should've also mentioned that I was trying to use the Start Choke buttons that are present instead of an ignition switch. If I understand your response, 2 of the wires are properly connected (ie. the white one to the safety switch and the black one to the points). I'm using the old solenoid that went with the '56 30. Unlike the shop schematic that shows 2, it has only one terminal that runs to the dash (for the start button). Can I use this solenoid and the Start and Choke buttons? If so, please tell me how.

FrankR
Posts: 3154
Joined: Tue Mar 10, 2015 6:32 pm
Location: Florida

Re: Big Twin 40 safety switch wiring question

Postby FrankR » Tue Apr 17, 2018 10:53 am

Arrgh, I should have known you were attempting something other than standard. You really ought to use the correct solenoid. That 6V one is wired differently and probably will not last long on 12V. Yes, it can be gerry-rigged to work with a resistor, if you know what you are doing. But by using the correct wiring scheme, you will maintain the function of all the related stuff...except the kill (ignition off) of the key switch. Yes you could kill it with another push button, substituting it for the two "M" terminals.

FrankR
Posts: 3154
Joined: Tue Mar 10, 2015 6:32 pm
Location: Florida

Re: Big Twin 40 safety switch wiring question

Postby FrankR » Tue Apr 17, 2018 10:59 am

If you want to use a push button for start, attach that white wire that would normally go on the "S" terminal to one side of the push button. Then you need to supply power to the push button by running the other side to the large + battery cable at the solenoid.

WetWillie
Posts: 96
Joined: Fri Jul 22, 2016 2:59 pm

Re: Big Twin 40 safety switch wiring question

Postby WetWillie » Tue Apr 17, 2018 8:03 pm

Well Frank, ya talked me out of going with my original plan. I'll get a 12V marine solenoid and keyed ignition switch post haste and wire it as per the schematic. Fwiw, I was trying to avoid running additional wires and ignition switch. Wanna suggest a vendor for the solenoid and switch?

Jeff Register
Central Arizona Chapter President
Posts: 1029
Joined: Wed Mar 11, 2015 7:19 pm
Location: Mesa, Arizona

Re: Big Twin 40 safety switch wiring question

Postby Jeff Register » Tue Apr 17, 2018 8:15 pm

That's what I enjoy electrical....the smoke test, hot. Had a 6 V starter in my 42 Dodge power wagon & earth mover batt & limo genny. Starter always spun. Understand the theory before building mismatched, :)
No worries,


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