Using a digital tach

[ajsupra]

Hello everyone,

I'm contemplating using a small digital tach/hour meter in my boat. My goal is to NOT cut a large hole in the dash to mount an analog tach, but to instead mount one of these units.

The instructions seem to only require the lead to be wrapped around the spark plug wire for inductive reading of engine rpm.

However, my 1975 Evinrude has the grey wire in the control box for a tach. I can't be the first guy thinking of running this lead to the factory tach wire. I'd rather not have to run the wire through the harness to the engine to get the signal.

What signal is provided to the grey tach wire... is it just a cylinder 1 firing signal? Just trying to understand if this would suffice.

Thanks

-Aaron

 

[Boobie]

Won't work as you have two different signals and two different tachs.

 

[ajsupra]

How exactly do you mean I have two different tachs and two different signals?

Simply asking if the signal at the grey tach wire in the control box is a cylinder 1 firing signal or some other signal.

 

[Boobie]

One tach picks up signals off of the spark plug wire and the other off of the alternator.

 

[fdrgator]

I think you are asking if you can use the WIRE, not the signal source. Of course you can. Just disconnect it at the engine end and reconnect it to your pickup.