Lister D magneto issues

Hi all

My Lister has a SR1 magnito, which was seized solid. After a good while I now have it spinning lovely but producing no spark. I have clamped the spark plug to a head bold to ground it, cleaned all the points and swapped out the condenser for one I had in my box. I'm using a drill to simulate the engine, and im getting sparks at the points, but not the plug. My assumption is the coil is probably dead. At the moment funds will not support a replacement mag or a rewind, but previously owning a 1988 mini, I have an old coil in my box. It's the one shaped like a long can with single ht lead in the middle and 2 terminals either side.

My curiosity was, would it replace the coil temporarily until life throws me some luck?

If I attach the wire from the points to the live terminal, and the wire going from the original coil to the little bolt on the casing goes to negative, attach lead and plug and spin it up, I'm getting a beautiful bright spark.

Apart from offending the traditionalists for a while, will this be OK?

Of course it will be OK, a running engine is better than a doorstop

I agree, and will try and make it aesthetically pleasing lol.

Working engine > engine doorstop
Engine doorstop > that piece of card we all fold up and wedge under there lol

But does anyone know how it's working? What is the cab type coil stepping up with no 12v battery supply? Surely the original coil must be producing some charge but not enough to jump the plug. I'm happy I have something working but it's badgering me how lol

Wot blue cat said! My first project (Villiers MK10) still has a car HT coil.

https://www.smokstak.com/forum/threads/coil-ignition-without-a-battery.117351/

I did read that after. I'm assuming my coil is charging but not enough to jump the spark plug. So it's providing the shot to activate the coil. I did put my meter and it was coming back as cankered (no good) I'm really happy it's working but unhappy I don't know how. Appreciate the link, it's handy to know that the magnito wouldn't write the engine off.

As to how it works. Moving a conductor through a magnetic field generates a current.  When the points open the current collapses and you get a voltage spike in LT circuit. HT side just acts as a transformer to up the voltage. When you put the car coil in series with LT side of magneto it becomes part of the same LT circuit  and you have, effectively, created a new transformer.

Have a look here also:   https://ukengineforum.forumotion.com/t6186-more-ignition-experiments.

PS If you want to amuse/baffled the kids/granny try getting a couple of those tiny but powerful rare earth magnet and dropping one down inside a straight length of copper pipe and simultaneously dropping the other one in free air. The one falling down the pipe will hit the deck later.

https://www.youtube.com/watch?v=uh0bbW6S3BY