I upgraded the ignition system of my 1987 Supersprint 1700 from a Lucas electronic system to an Aldon Ignitor. I have everything working except the tach.
The tach is a VDO 333/230/147/3 and has three spade poles on the back labeled +, 1, and -. I assume + and - go to 12V+ and ground. My guess is that 1 goes to the negative side of the ignition coil, which also goes to the distributor. When I looked at the wiring diagram for the car there are two white and black wires going from the 1 pole on the tach. One goes to the negative side of the coil and the other into the Lucas module. I suspect that I just need to unplug the old spade connector from the tach and run a wire to the negative pole of the coil and forget about the wires from the electronic ignition, both on the tach and the negative pole of the coil.
I believe that what is preventing the tach from working is the white and black wire that goes to the Lucas module. It is either holding the voltage high or low all the time.
I should mention that I don't want to cut any of the original wires in case someone wants to bring the car back to completely original condition.
Does this make sense?