What drives the tachometer in the 72 914?

Elves.

It's actually just a simple gear inside the transmission that rotates a cable. Old school.

-m.

The speedometer is cable-driven, not the tach. Or maybe the earlier cars had a mechanical tach?

fail!!

it's driven off the points side of the coil

Oh right. My mistake. I was thinking of the odometer cable. Sorry, I changed to a new brand of crack.

I have a wire there that I have not connected yet. So you are saying it connects to the negative side of the coil? That's the side I have the points connected to. It makes a very small spark when I touch it to the negative side of the coil. Back when I was trying to get the engine running, when I connected that wire it kept the engine from firing. So I've left it disconnected?

Now that was funny...

Should be a black wire with a purple stripe. Make sure that it's the same wire that connects to the back of the tach, and that it's on the right plug back there.

If it is the same wire (the "continuity tester" function on your multimeter will help show that, or the ohmmeter function) and it's plugged into the right place, and it isn't shorted to ground somewhere, then your tach is hosed.

And yes, it's supposed to connect to the same side of the coil as the points wire.

--DD

Thanks DD! That was the most clear and concise instructions I have received to-date! I can do that. So...what is the "right" connector on the back of the Tach?

I forget the numbers, but you can look at the nice color wiring diagram over at Pelican Parts. BTW, the wire in question is a relatively thin black wire with a purple trace. DO NOT attach the thicker black wire with the red trace! You'll waste the points and the condenser, as well as the point wire! All the smoke will get out and they won't work any more.

The Cap'n

Nope the big wire is on the positive side of the coil. I'll chase down the smaller one and make sure it goes to the back of the tach when I get home tonight. So the tach is just a pulse meter.

i swapped the brown grounds to the terminal labelled - and put the tach wire on the opposite terminal and got a somewhat fluctuating rpm reading on the tach but the engine clearly was missing and running rough until I disconnected the tach wire from the coil at which point the engine started and ran smoothly again. I need to find a visual of the connections on the back of the tach meter.

Tach wire goes from the neg. side of the coil to the relay board(black with purple trace). This is terminal one on the coil. See link to diagram: http://www.pelicanparts.com/914/parts/Elec...lectric_73C.jpg
Your coil is item 6 bottom right regulator plate is bottom left

From there it goes to the regulator plate though the 12 pin connector at the back. Pin number 5: http://bowlsby.net/914/WiringHarnesses/HarnDia_IGN_73-76.jpg

Out the other end of the Regulator plate through the 14 pin connector through pin 7 then the harness to your tach again conncting to terminal 1: http://www.pelicanparts.com/914/parts/Elec...lectric_73A.jpg
Tach is item 22. The 23 on the diagram at the end of the wire is to identify the carryover from the other diagram.

I count 6 connections to cause a problem. Four at the regulator plate alone. Make sure they are all clean. I've had way too many problems caused by a dirty Reg. plate.