Tachometer

[jackf]

My 73 coupe came without a tachometer from the factory.  The previous owner has wired in an after market tach.  It works.  I have a refurbished cluster with a factory tach.  My plan is to put white face stickers on the speedo, fuel gauge and tach, upgrade to LED bulbs and install.  When I plug everything in, will it work?  Is there a difference in the wires going into a non tach circuit board and a tach circuit board?  Thank you,

 

[midlife]

My 73 coupe came without a tachometer from the factory.  The previous owner has wired in an after market tach.  It works.  I have a refurbished cluster with a factory tach.  My plan is to put white face stickers on the speedo, fuel gauge and tach, upgrade to LED bulbs and install.  When I plug everything in, will it work?  Is there a difference in the wires going into a non tach circuit board and a tach circuit board?  Thank you,

Yes, there is a substantial difference between the two.  Ford tach wiring is in-line with the signal from the ignition switch to the coil, and is a current-sensing device.  That signal comes from the + side of the coil.  Aftermarket tachs are voltage sensing devices, and get their signal from the - side of the coil.  Furthermore, they need an external power source that is not found on the Ford tach.

 

[Stanglover]

Ditch the factory tach as your harness connector will be different too. Go to Rocketman's Classic Cougar's website (link is below the tech section) and talk to Bob. I'm sure he can help with an upgraded tach conversion. I bought a tach with idiot lights and it works great and look original. ( other than when I turn the key!!)

As for upgrading to LED's, I suggest Hi-Po Parts Elite series LED's, #FC7173FM-EL2. www.HiPoParts.com .There are colors if you prefer. These are way better than the Extreme series. Just a word though, DO NOT use an LED in the ALTERNATOR socket if you go this route. You MUST use an incandescent bulb or the circuit can be damaged.