1972 Johnson 50 ESL , Can you add a tach on this motor

I'd like to add a Tach but since it didn't come with one I'm not sure what kind you need and where you could safely connect it.

Re: 1972 Johnson 50 ESL , Can you add a tach on this motor

There are cheap tachs that go on the sparkplug wire, it counts pulses.

Re: 1972 Johnson 50 ESL , Can you add a tach on this motor

look and see if your control box has a three prong plug in on it. If so that it where the wiring harness plugs in for the tach. you can still get the harness reasonable and buy a tach at West Marine or Bass pro.

Re: 1972 Johnson 50 ESL , Can you add a tach on this motor

jonesg said:

There are cheap tachs that go on the sparkplug wire, it counts pulses.

Click to expand...

Not just a tachometer but an hour meter also.... Inexpensive, easy to hook up and bullet proof...


http://www.tinytach.com/tinytach/index.php

Re: 1972 Johnson 50 ESL , Can you add a tach on this motor

Fact is that there are many suitable tachs available for your motor, including right here at iboats.

Most of them require a switched 12 volt supply, a ground, and a tach signal. All are available inside your remote control. 1972 models were not equipped with a plug. But the wires are in there, waiting for you.

12volts is at the purple wires on the key switch.
Ground is the black wire screwed to the control box.

Just add your tach wires under the screws already holding the purple and black.

Finally, the tach signal is the gray wire that is just loose in the control--splice your tach wire to it.

Last step is you have to tell the tach how many pulse signals you have per revolution. There will be a switch on the back of the tach for that purpose. I am reasonably sure the 50hp is 5 pulses/10 pole. But verify that.

The tach counts the pulses from the alternator and works very well.

Re: 1972 Johnson 50 ESL , Can you add a tach on this motor

Thank You all for the help, that was outstanding info, tach would be quite helpful while doing a tune up and getting the RPM's correct!

I'll pick one up here and see if I can install it as was recommended

Thank You all!

Re: 1972 Johnson 50 ESL , Can you add a tach on this motor

Tiny tachs and the like are great for motors that don't have the necessary circuitry for pulse type tachs. Since your motr has what you need for a pulse operated tach, that's the route I would go.

The wiring connections that you need to mae are as follows.

. Purple wire (from control box) goes to the "IGN" post on the tach.

. Black wire from a suitable ground goes to the "GND" post on the tach.

. Gray wire (from control box) goes to the "SND" post on the tach.

Your tach may have a post for an internal lighting circuit. If it does, run a red wire from the switched side of your panel or running light circuit.

Don't forget to set the correct number of pulses. I don't know the proper setting, but F R is probably right.