I wired up a lumenition ignition and it works fine but the tacho is dead. The tach is still wired as the diagram shows and the resistor wire then proceeds to the plus terminal on the coil. Apparently the electrical impulse has been changed somehow making it hard for the old tach to read. What have others done to solve this problem?

Is you coil the 9v or 12v ??

Does the Lumention run a multiple spark like the MSD boxes do as that could be pulsing the coil more than once per cycle confusing the original tacho.

I have been thinking of the same conversion & I do have a Lumenition but I also just bought a Pertronix kit instead as I believe this is the conversion kit used in the UK Capri electronic ignition conversions(Motorcraft Disy)of which does not affect the tacho, but I am more than a few weeks away from testing either, so I will be interesting to see how you with yours.

Kev.

Ron,
I have removed the oroginal tacho and replaced with a modern electronic circuit board type unit. To achieve the original look the old capri tacho needle is secured back onto the new tacho. With the use of a modern type tacho unit it is as simple as running one wire to the coil. Once complete their is no way of telling the differnece unless the dash cluster is removed.

Have you tried a hand held one across the coil to test the signal from the coil. Dont know anything about lumenition but I would think the coil would still cycle the same.

You mention the resistor wire. Is yours the car I saw a while ago that has an external resistor now? Have you checked that the resistor by pass circuit is wired correctly and that the old resistor wire was removed correctly? (might not be your car I'm thinking of)

Kev I have a pertronix 1868. Works fine but from memory the hole was a bit big and had to be sleeved. I think they just used some heat shrink on the shaft and glue. Shultz's put it in when they were adjusting my timing weights. Was a long time ago but I remember something like that.

Thanks guys, your info gave me food for thought. It looks like several ways to fix this problem, which is basicaly when electronic ignition is fitted to cars with points systems the shape of the electronic impulse is changed so that the old tachos have difficulty reading it.(Electricity not my specialty so cant explain it better).
Being a common problem most manufacturers have adapters made that will get the tach working again. I bought an msd tach adapter so we will see how that goes, cost $85.

The msd tach adapter looked like a good idea until I realized it would short out the system killing the module. So no go there. Now my nephew who is a ham radio guru reckons he can fix it. I left him muttering about diodes and capacitors and round waves and square waves so there is hope.
On another note lumenition have been selling their ignitions for these cars for nearly forty years and I cant believe they haven't solved this problem a long time ago. Im a little peeved at them right now.

I finaly decided to have a new circuit board fitted to the v6 tach. At least now I have a tach with new electrics and recalibrated, should be accurate and trouble free. And still looks totaly original.
Lioel otto instruments,qld. cost $200.