Tach Question

Ok, so last week I bought a used Faria Tach for my 1985 70HP Johnson. It's a model # TC9430C. I also got a wiring harness so I can plug into the control box. I'm confused though. The engine manual says there are 6 magnets in the flywheel. This leads me to believe this is a 12 pole system (6 pulse). Through reading I surmise that #poles/2 = pluse rate, however the back of the tach says to have the setting on 5. Problem is the tach doesn't seem to work on the 5 setting. If I set it to 4 (10 pole) the tach seems, SEEMS to operate. Also the tach has a 6 setting which is NOT listed on the back.

My question is does anyone have any idea what's going on here. I'm tempted to leave it set at 4 but I also want to make sure it's giving me somewhat accurate readings.

Please help me wade thru this.

Denny

Re: Tach Question

It will be a 12 pole setting. Had the same deal with my 1988 60hp the book said it was 10 pole but that is for later model engines. 3 cylinder motors are 12 pole.

Re: Tach Question

This may be a coincidence, but I too bought tach of this manufacturer. It would not register correctly when placed on 6 pole as it appeared the arrow was pointing to. I moved the setting around to all the settings and it was not correct on any of them.
The tack was new, but very old. I set the dial of the pointer to a location oposite of the 6 Pole setting that it should have worked correctly with, and the tach read perfectly. Seems the dial indicator was oposite of what I thought it was.

Re: Tach Question

I installed a new Faria tach two years ago for my 1985 70Hp Evinrude. I don't have the info here as it is at our cottage but I'm sure I remember the instructions stating that a 6-pulse sytem (as yours is) should have the dial setting at #5 on the back of the tach. I remember because this seemed odd to me.

My tach has been working perfectly as confirmed by may digital timing light.

Try #5. If it doesn' work, something else is probably wrong.

Good Luck!

Re: Tach Question

Thanks for the replies.

You are correct gyoung. The back says to use the 5 setting. I'll try it again after I get it installed in the dash.

Denny