Yes, by far most of the tachometers work in combination with a 123ignition. RVI type tachometers manufactured by the Smiths Company, will need to be connected differently. The red wire must be connected to the switched plus of the ignition switch instead of the ignition coil.
The reason: the current passing through the ignition coil, to create a spark, is measured by the RVI tachometer. It is the current for the computer in the 123 ignition that runs through the tachometer that is causing the wrong indication.
Solution: The power needed to run the computer in the 123 ignition will no longer pass through the tachometer if you connect the red wire (positive) of the 123 ignition to a directly switched positive.
How: this switched positive can be found with a test light by, for example, measuring the fuses and switching the ignition on and off.
If you have another type of tachometer that responds '' wild '', it is best to put a diode (1N4007) in series with the tachometer. Note, the line on the diode must point to the tachometer.