Re: Pertronix and Powerspark
Posted: Thu Dec 10, 2020 10:52 pm
In very inaccurate terms, the standard tacho work by "counting" current pulse to the coil. These are normally triggered by the points, so relate to engine speed.
If you power an electronic ignition module off the coil, the pulses relating to its operation also go via the tacho and you can get strange behavior of the tacho. Particularly so with 50 year old electronics in them.
The possible fixes are:
- Don't power the module from the coil, add a separate switched live for it.
- Rebuild the tacho electronics, especially the capacitors
- Replace the the circuit board in the tacho with a RVC one, like spyida. This will also require some re-wiring and calibration of the tacho.
If you power an electronic ignition module off the coil, the pulses relating to its operation also go via the tacho and you can get strange behavior of the tacho. Particularly so with 50 year old electronics in them.
The possible fixes are:
- Don't power the module from the coil, add a separate switched live for it.
- Rebuild the tacho electronics, especially the capacitors
- Replace the the circuit board in the tacho with a RVC one, like spyida. This will also require some re-wiring and calibration of the tacho.