Magnetos and electonic ignition

[Guest Ken G]

There was an interesting series of messages last year on ignition timing. I have just had a disaster in that the magneto died, and I had to send the armature to an expert in England. Strangely, it appears not to be an open-circuit winding but something within the output slip-ring, but I cannot remove the ball-race that is an interference fit on the shaft and has to be removed before you can get at the slip-ring. Three attempts at making tools all resulted in destroying the tools (but fortunately with no damage to the bearing).

Anyway, having failed to get any response on other forums ... has anyone replaced a magneto in a 1920s car by electronic ignition, and if so, how? I think it ought to be possible to use the existing contacts and distributor, but to use a points "amplifier" and a conventional coil. The brush that makes contact with the points would not stand a normal coil current, so the amplifier is necessary. If necessary I can probably design something (I am an electronics engineer), but before I start I would like to know what others have done. My object is not necessarily to replace the magneto for normal running but to have a back-up that can be installed on the road. (The alternative is a spare magneto, but ML CG4 magnetos are not easily come by). I have now twice arrived home on a flat-bed truck (most ignominious, and very difficult to get the car into the sloping garage) and I want to be able to get home under my own power.

Ken G, 1925 Rover 16/50 (San Francisco)