OMC tach 122923

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OMC tach 122923

Postby amuller » Thu Aug 09, 2018 2:02 pm

Picked this up at Tomahawk. Can't remember if I paid $1 or $2 for it.

In any case there are four leads: blue, black, gray, and purple, and a pulse/rev dial with settings of H, 2,3, 4, and 6.

Can anyone point me to a data sheet for this, or tell me which wire goes where?

And will this tach work with an early 70s CI ignition? I vaguely recall that there was a special tach for those. I also think there is a gray wire from magic box, not otherwise used, that might be for the tach.

Thanks for any help.

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Re: OMC tach 122923

Postby FrankR » Thu Aug 09, 2018 4:15 pm

Well the wires are simple enough. Blue to running lights (dial illumination) Black ground, gray pulse signal, purple switched 12V. I think it might be an universal tach, but that's guessing.

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Re: OMC tach 122923

Postby BillW » Fri Aug 10, 2018 5:43 am

Early seventies should have a rectifier in the charging system, if I remember right. You would hook up the wires as Frank said, hooking the gray wire to one of the yellow wires at the rectifier, preferably the one with a gray tracer. I am going on memory but I believe you'd put the switch on 6. Then the tach should work, providing that the charging system is working to start with.

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