Airguide Tach

[klicknative]

Yesterday I won the ebay bid on an Airguide outboard motor tach to use with my '69 40HP Evinrude Lark. I did a search and read the posts about it here on the Johnyrude forum but I want to clarify the connections. The gray wire marked tach ground goes on the negative (-) terminal on the tach and run a wire from the positive (+) terminal to one of the wires marked "MAG" on the ignition switch. Correct? Does it matter witch of the 2 terminals I connect this wire to? From what I understand when the key is in the "off" position it closes this circit and grounds the coils. Correct again? So if the tach doesn't work try the other "MAG" terminal?

 

[klicknative]

Re: Airguide Tach

bump

 

[klicknative]

Re: Airguide Tach

2nd bump. I expect my tach to show up in the next day or 2 and hoping to have it installed by this weekend. I'd hate to see my $33.50 go up in smoke.

 

[6228SH]

Re: Airguide Tach

Sorry if this reply gave you false hope of an answer-I am awaiting along with you in case I come across a tach myself-do you by chance have a link to the auction so I can check out the pictures?

 

[klicknative]

Re: Airguide Tach

Item number 140136485264. I'm pretty shure you can search and find it. I tried to post photos but I couldn't edit the file size down enough to work.

 

[iwombat]

Re: Airguide Tach

+ on the tach to the grey wire in the ignition.
- to ground.

 

[klicknative]

Re: Airguide Tach

The gray wire grounds to the powerhead. Looking at the wiring diagram in my OMC shop manual the 2 black wires at the ignition switch each go to a set of points. So, it looks like I'd get a signal off of one of the black wires.

 

[iwombat]

Re: Airguide Tach

Sorry, I had to go back and read what you were dealing with again.

Those two black wires are your kill switch they're used to ground out your ignition system. I don't think you really want to be using those for your tach signal.

So, we need some info on which lead in the control box is signal for the tach. Since I've never hooked up one of that vintage to a tach I'm beyond my knowledge here. However, I got the tach side covered.

- ground
+ tach signal


Tach signal color anyone?

 

[klicknative]

Re: Airguide Tach

The way the switch works is when the key is in the "off" position the points ground each other out killing the engine. They open 180* from each other so the open set is grounded to the other one. I'm thinking it works like an automotive tach, getting a signal from the neg (-) terminal on the coil from the points opening and closing.

 

[iwombat]

Re: Airguide Tach

It's a good theory as long as there's enough impedance in the tach to not ground out your coils. Probably a safe bet, but I've got no experience doing it.

 

[klicknative]

Re: Airguide Tach

Well, I think I'm back to square 1. I just got it in the mail and the small print on the face says it's for a 6 cly motor. Good thing you can sell on eBay too.