Hooking Tacho up to FD Coils ?
 

I'm in the process of fitting a Microtech LT8 into the 1st gen to use it to control my ignition and hopefully improve the running on LPG but I' struggling with the tacho wiring.

Its easier to get hold of FD ignitors and Coils than the FC version, the wiring is done and the car does fire up and show a spark on each lead.

The Microtech manual says to use the Leading coil (-) to get the signal but it didn't work. It worked for the sensor for the LPG switch so it doesn't shut off after 2 seconds of running !

Do I just wire it to the (-) of one of the FD trailing like it shows in the 1st gen manual where there is a common coil ?

Any help would be greatly helpful.

Shaun