How do I hook up an old outboard tach?

[Laker99]

I am refurbing a 1965 Mark Twain that had a really cool set of gauges by Aqua Meter which I am cleaning up and rechroming. The boat had a 1964 90HP Evinrude. I will be putting a 1980's era motor on this boat when I am done with installing new stringers, floor, transom, and interior.

I know that modern tachs have switches on the back to set the poles and I believe most of them are set on 12 today. This tach does not have any settings. Does anyone have any idea if I can use this tach on a more modern motor? The only wires are red and black and there is a tag that says run these to the battery. And then there is a single wire with no instructions where that goes. I'm also wondering if a tach that sat out in a boat yard uncovered has much chance of working.

The openings in the housing are 3 inches. I have looked all over but I guess no one makes smaller sized tachs and speedos since the standard is 3 3/8". Ideally, I would like to put a new speedo and tach in these old housings since they are very cool. I would appreciate any help someone can give me on this.

 

[ezmobee]

Re: How do I hook up an old outboard tach?

May as well give it a try and see if the readings it gives (if any) seem legit. Red=positive, Black=negative, the third wire will go to a gray wire in your newer motor's control box (tach pulse).

 

[gm280]

Re: How do I hook up an old outboard tach?

I like your initiative in making old gauges work again. And for the record any old gauge can be rebuilt IF you have the knowhow and the willingness to do all the very precise intricate type work. That could be simply re-connecting it up to the correct terminals or as in-depth as even rewinding the gauge windings if need be. All the actual electronic parts inside can be replaced with new parts as well if need be. It just depends on how much work you are willing to do to get it working again. Remember, most all gauges were originally built by somebody at one time. So it can be tedious but not impossible...think watch makers...