Evinrude 1977 55hp - tacho wiring

[Qld_Kev]

I want to wire up a tacho to my boat to check WOT revs. <br />A. Are car tachos ok, what cyl do you put it in?<br />B. Which wire do you pick up on the engine/throttle housing.

 

[WillyBWright]

Re: Evinrude 1977 55hp - tacho wiring

Inductive pick-up car tachs will work. Doesn't matter which plug wire you attach to. Since they fire differently, a 2-stroke will show double RPMs. So if it reads 3000, the motor is running 1500. Problem might be the scale. 5,500 RPMs doubled will be 11,000 on a car tach. Might not have enough digits on a digital, or enough sweep on an analog.<br /><br />Outboard tachometers work off the alternator. The wiring is different. Black is -, purple is keyed +, blue is the backlight, and gray is the signal. The gray wire attaches to one of the yellow alternator wires to provide the signal. That signal would be meaningless to a car tach.

 

[Qld_Kev]

Re: Evinrude 1977 55hp - tacho wiring

Thanks, may have to get the marine tacho. Will have a look on the weekend; and give the wiring ago.