Question on installing tachometer on 55 Johnson...

[wolf66]

.....found a very cheap after market tach on Amazon, ($15!) but i need to know the firing per revolution per spark plug to set it up...

1977 Seahorse 55 2 stroke.... do i want

A. spark plug fires twice per rev
B. fires once per rev
C.fires every other rev

I feel like i should know this but don't.....sigh

 

[racerone]

The sparkplug fires once per revolution--------------------------Most factory tachometers run off the alternator pulses.

 

[wolf66]

Thanks!
This one has 1 wire that grounds to the motor and one that wraps around a sparkplug wire...also has a hour meter and runs off its own lithium battery, not bad for $15 if it works...