Yeah car is all wired up and running, just needed to know how to hook up the tach. Does the tach go inline before the ballast resistor on the power side, or after the resistor but before the coil?

After the ballast but before the coil would be safer?

Yes the wire that wraps around the inductive pick up in the back goes to the +ve of the coil, the -ve of the coile goes to the points or transistor depending on what's switching it.

Let's just say it's going in a bare shell with an engine with 2 wires for the ignition system (wire to batt+, wire to coil+, joined at a switch in the cab, it's a speedway car), where do the wires for the tach go? (ignoring the backlights)

Does the black and white wiring go inline (connected in series) in the wire to the + side of coil?

Anyone ever fit an aftermarket stepper motor tach inside the body? I'd be at pains to ruin a working tack to try....

Quote:

It uses this factory wiring which is in all Coupes and Sedans:







See Wiring, tachometer section.

there are 2 wires taped (yellow tape-I think?? ) to the loom in most 1200's that are the tach circuit inductive loop as Benny described. usually located close to the bend where the loom turns down the RH corner of the back side of the dash.

pull the diagram & look, you'll see them in a dashed line on the schematic....

Righto, what wires connect where, and in series or parallel etc etc etc?

The tachs in our B110 are triggered via an inductive loop, there is no direct electrical connection. The pointer is able to sweep through ~ 270 degrees. after that it just maxes out at the and will not move any futher due to physical limits.

The cct is able to be recalibrated to different scales but it is worth noting that these type of tachs inherintly have a percentage error. I get my tachs calibrated and certified by a qualified instrument repairer, [just because i am a fuss pot]. This also includes re-balancing the needle and adjusting the counter balance weight and tension spring . Due to this precentage error it is far better to be spot on [indicating] at say 8,000 RPM where it matters rather than at idle speeds.

In recent times I have been sucessful in making reproduction 10,000 RPM competition tachs.

I'm also interested in knowing if the tach can be calibrated. I have on order a photo-tach counter, they're common in model aircraft circles and are pretty cheap these days. Be good if I can use that to calibrate the tach. I know there's a couple of screws on the back but I'm not sure what they're for.

1. What happens when you go past 8000rpm? Does the engine cut out at all or does the ignition remain unaffected?

2. Installation instructions ie. what wire goes where, in a car which has no wiring in the cabin? Are there certain vehicles with ignition systems in which this tacho cannot be used?

3. I constantly hear about the tachos being inaccurate. How can this be tested, and how can any inaccuracies be rectified?