1979 Johnson 85HP tachometer

[healey8390]

Trying to find a tach for my 1979 85HP Johnson. I was told I need one with the right poles? One site says 6 poles so I just want to confirm here, thank you.

 

[Joe Reeves]

Re: 1979 Johnson 85HP tachometer

That would be a tachometer that operates off of a 6 pulse alternator (yours). It would have a numbered dial on the back of it which you would set to number 6.

It normally has four wires leading from it:

Red = To 12v source
Blue = To light switch
Black = To ground
Gray = To sensor

 

[F_R]

Re: 1979 Johnson 85HP tachometer

A bit of terminology here. It has 12 POLES, which produce 6 PULSES. But you are on the right track. Just think 6 and you will be ok.

 

[V153]

Re: 1979 Johnson 85HP tachometer

Ya if'n it's an OMC tach the correct dial setting would be 6 pulses (12 pole stator). Personally I'd shop around & find a decent period correct OEM tach vs buying new. They seem to work better?