'58 Johnson 18 kill switch

[petrolhead]

I want to fit a remote kill switch on my dash, am I right in thinking that the kill switch on the front of the engine just grounds the two wires from the points/coils?<br />And to fit a remote switch I'd need to take a lead from ground to the dash, through a push-to-make switch, then back to those two wires?<br />Or is there a better way to do it?

 

[rickdb1boat]

Re: '58 Johnson 18 kill switch

Hot wire from coil to switch, the other from switch to engine ground will do it...

 

[Paul Moir]

Re: '58 Johnson 18 kill switch

The switch on the front connects the magnetos together only - it does not ground them. They ground out through each other.<br /><br />Best way is to connect the anodes of two diodes together and connect each cathode to each kill wire. then run a single wire to the dash from the anodes, and ground it to kill spark on both cylinders. The advantage is you only have to run one wire, since you invariably have a ground somewhere around the dash. The diodes need a PIV of at least 200v. But if that's Greek to you, then the best way is either rickdb1boat's way (kills spark on 1 cylinder) or run two wires like the kill switch on the front.

 

[petrolhead]

Re: '58 Johnson 18 kill switch

OK Paul, that definitely sounds like Greek, or possibly Double Dutch to me!<br />I don't think there's anywhere to ground anywhere near the dash, it's an all wood homebuilt boat and I'd need to run a ground wire back to the engine I guess, unless I can ground to the steering wheel which is connected by s/s cables to the motor?<br />I think I like the idea of extending the two kill switch wires to a switch on the dash, if I understand you correctly the switch just has to connect the two wires together yes?<br />And does it need to be insulated like the one on the engine, is that rubber boot there to stop me being electrocuted or just to waterproof the switch?<br />As you can probably tell I'm a bit of a duffer when it comes to electrical stuff!

 

[Paul Moir]

Re: '58 Johnson 18 kill switch

You understanding of the kill switch is correct. <br />The boot on the switch is just to keep the water out of the switch. The metal switch cap is isolated from the electrical contacts inside it.<br />But I'll warn you that you can get a refreshing jolt from the magneto (kill) wires when the engine is running. So if you use RickDB1Boat's method, use a proper ground. Say if the cables didn't make such a great connection once, and while killing the engine you bumped the (better grounded) engine throttle controls, you could receive a zap via the steering wheel.<br /><br />My old 28hp was rigged up to ground out one cylinder only, and it took a while before the engine would completely stop. Mind you it has the 50lb steel ring gear on it's flywheel, and I don't think your '58 18hp would have one unless it also has an electric starter on it.

 

[Chinewalker]

Re: '58 Johnson 18 kill switch

One suggestion - install a 2-prong plug to facilitate disconnect of the forward wires at the engine. Should you need to remove the engine from the boat all you have to do is unplug it since the wires aren't hard-wired into the existing switch system.<br /><br />- Scott

 

[petrolhead]

Re: '58 Johnson 18 kill switch

Good idea Chinewalker, and a pretty obvious one when you think about it, which I probably wouldn't have done!<br />I remember you gave me some good advice when I first got this engine last year, so thanx again.

 

[rwise]

Re: '58 Johnson 18 kill switch

I just did the parallel the kill button on my 35hp works fine, much better than "choke to kill" myself, I would not use the diodes (sorry Paul) the circut would work but IF the diodes shorted it could leave you stranded! Sometime the simple way is the best, at least for me.

 

[Paul Moir]

Re: '58 Johnson 18 kill switch

I should clarify what I did rwise - both diodes are accessible underneath the cowling rather than the flywheel, so a simple snip should get you going again if there's a problem. <br />Besides, having two diodes fail shorted on you would be extremely unlikely since they are not normally carrying current. If something did spike up on the coil's primary, say if the coil arcs over internally, then the diodes should simply avalanch rather than fail catastrophically.<br />But then again I suppose I'm from a generation that would rather put their trust in subtle quantum principals rather than dicey old fashioned things like mechanical points.

 

[rwise]

Re: '58 Johnson 18 kill switch

Paul, if I had the diodes and only one wire, I would do it that way (I'm cheap). Yes the chance of failure is low, I agree, (as long as the diodes are sized correctly) but then I see electronics fail every day just from being powered up! just a thought here but wouldn't both methods still have the mechanical switch, just a thought. Either way will work the same, use what ya got!