1978 35HP Seahorse CD + Tachometer

[riley2009]

Hello i have a Johnson 1978 35hp Seahorse CD, ive just purchased a vintage OMC Alternator tachometer, assuming the age of the tach and the age of age are around abouts the same capitbility issues arent a issue??? The tach its self has 2 wires Grey and black

GREY = Tacho Signal (I ASSUME)
Black = Ground?

I guess this tach works directly from the signal cable where alot others have 3 or 4 wires so they turn on with the ignition? also this one has 2 connections either side of the blub holder so this is the 12v supply to the illumination i guess? (Silly question i know but thought id check )

Just looking for guidence really not to sure on these gauges/tachs

 

[riley2009]

Re: 1978 35HP Seahorse CD + Tachometer

any ideas?

 

[oldslowandugly]

Re: 1978 35HP Seahorse CD + Tachometer

I had one of those that came with a 71' 125hp. Yes, only 2 wires, grey to tach terminal from stator and black to ground. It's usually yellow with grey stripe wire on the rectifier mount on the side of the powerhead. I kept it as a tester for the charging system as it works off the stator and could test any hp motor as long as it had one.

 

[F_R]

Re: 1978 35HP Seahorse CD + Tachometer

riley, it doesn't have a pulse switch on the back, does it? If not, it won't work on your 35. Well, it will work, but will give false readings. Your motor has a 5 pulse alternator, and the tachs without a switch were for 6 pulse alternators.

Getting a tach with a switch will let you change it to match the motor.