Ignition system

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OK, I tried starting the engine last weekend, but no luck.

The main problem is the ignition system really. When the engine is hand cranked, there is no spark. This was last weekend.

In the last few days, with the help of Warren, we decided that the capacitor inside the coil is failing. After taking that out, by disconnecting it and wiring a modern one across the contacts, the spark improved a lot.

I can now create sparks about 5 or 6 mm long. BUT that’s when spinning at a nice speed. At crank speed it’s still hopeless.


Have been talking with a guy in the states about rewinding the coil. But with the new capacitor, I have the feeling that the spark isn’t going to improve a lot.

So I have made a decision to start using a modern car ignition coil.


Keep the best magneto

Today Warren and I have compared the two magneto’s to find the one with the best spark. This is the one I am going to keep as an original magneto; running independently.

The other magneto, will undergo a bit of a rebuild:

  • I will still use the distributor.
  • I will still use the contactor.

But that’s where it finishes for generating the sparks. What I am doing is using a modern car ignition coil, that feeds into the magneto where the old coil used to feed into the distributor. The contactor will still be used but now it will switch the external ignition coil, using the battery as a power source.


What this means is I will have nice big sparks, see photo on the right of at least 10mm, even at the lowest engine speed, that’s while cranking the engine.
This ignition system relies on a battery though, but I have a battery already, so no extra weight.

The second real magneto is still there, generating nice sparks when running, so that’s my safety net.

As an interesting extra thing, Warren is going to try to make an alternator of the magneto I am rebuilding, so basically rewinding that coil you see just above, to generate a supply for the charging the 12V battery. It won’t be much, but I might as well use it. The same alternator signal can be used to produce my tachometer signal, using some electronics circuitry…


Disassembling mag coil

I took the coil for the magneto that you see above apart today.

With this magneto I will be using its distributor in combination with the car high voltage ignition coil, but I am also going to use the rotor and the coil to generate power to charge the battery.

At least that is the plan. Warren, at work, is going to modify the rotor and rewind the coil. So today I removed the high voltage winding’s. Millions of winding’s, thin as a hair, or even thinner I would say:


Then found a massive capacitor between the high voltage coil and the primary winding’s:



With the beginning of the two sides of the “rolled up capacitor”

And the primary winding:


This primary winding will be used initially to do some measurements, but will probably be re-wound to get the right voltage for charging the battery.