Re: tach install on 1977 115hp mercury straight 6?
Pretty much any marine tach (auto type tachs won't work) with a selectable "pole" input (6 pole, 12 pole etc). Depending on the controller you have, all the tach signals you need should be right there already. You will just need a tach harness to run from the controller to the tach at the dash.
Re: tach install on 1977 115hp mercury straight 6?
Also if you plan on using an aftermarket tach which I did in my case I had to run my sending wire to one of the yellow wires coming from the stator.The brown connector on the switchbox doesnt work on the aftermarket Tach
Re: tach install on 1977 115hp mercury straight 6?
Actually, all you need to do is remove the brown wire from switchbox and connect it to either of the yellow wires on the rectifier. No need to run a new wire.