I am thinking of adding a tach on my 66 Fastback, but have never even attempted this. What wiring has to be done, what do you need to buy, etc? Would the hood wiring harness need to be changed or where does the tach get its information?

 

Check with the manufacturer. Find someone who has one like yours with an instruction sheet. If all else fails, here's what I've seen, but there's no guarantee that it will work for your tach.
Most modern tachometers have 4 wires, usually color-coded red, white, green, and black. The wires are connected as follows:
Red - connect to a switched ignition source, positive (+).
Black - connect to ground (-).
Green - connect to the coil's negative (-) terminal.
White, sometimes yellow or blue or striped insulation - connect to the dash light wiring if you want the tachometer lighting to work and dim with the dash lights. If the dash light circuit is too difficult to tap into or not worth the effort, it can be connected to a switched ignition source, same as the red wire, and the light will work whenever the ignition is turned on (this is howthey areusually connected).If you buy a new tach, there will be an instruction sheet that comes with it.

 

If you don't mind spending the coin, I highly recommend a Rally Pac with tach and clock.

 

So, the tach gets its information from the coil? Sorry, just don't know...

 

Yup.

 

Thank you Soaring!

 

The latest aftermarket Rally Pacs are wired up like the original ones, no wire to the coil. The tach is hooked up in series with the resistance wire between the ignition switch and the resistance wire. Ground, constant hot for the clock and instrument lights make up the rest.
Jim

 

Jim,

Are there multiple manufacturers of the RPs or just one to your knowledge? I see them available from Sac Mustang on Ebay for $369 as well as a place called Autokrafters for the same price. If I get one from Sac Mustang it'll cost me an extra $30 in tax but there ad does list theirs as officially Ford licensed. I can't tell if the Autokrafters one is the same (only available) model or not.

BTW, I see that they now have the clock with the same original 'mechanized' ticking like they did stock, unlike the quartz conversion I did on the RP in my '65 GT.

Thanks!
Jeff

 

Jeff,
Don't know who's making them now (it came in a brown paper bag) and all the paper work is gone, didn't add up to much anyway. Try to e-mail NPD for info. I bit the bullet and got mine from them. And again, I was pleasantly surprised.
Jim

 

So what is your advice as to where to hook up the wire if you don't hook up a wire to the coil to operate theTach? Your description is vague.