Vintage Mercruiser Tach Pole Question

[putt-putt]

Hi,

I have purchased this tach for a restoration https://www.ebay.co.uk/itm/233881858646?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2648

The painted on lables seem to have worn off, can anyone give direction as where the 12v, signal and ground go?

TIA.

 

[alldodge]

Unable to say for sure, but it will be the two located below the retaining bar. Take a ohm meter and see which one provides zero ohms between the case of the meter. If one does that should be ground.

 

[Chris1956]

The real old tachs (1973 and earlier) had only 2 connections. One would go to the switchbox, and the other was likely ground, however, you had best find some real old wiring diagrams to make sure.

 

[putt-putt]

Is that what i have Chris?

 

[Chris1956]

I cannot tell from the picture, but it doesn't look like a newer style tach. How many connection does it have?

 

[alldodge]

I cannot tell from the picture, but it doesn't look like a newer style tach. How many connection does it have?

If you go to the link then look at the pic of the back it shows how many

 

[Chris1956]

Looks like a 3 wire tachometer. Also looks pretty crusty. Does it work, and why do you want such an old one?