I have recently finished a conversion of an ML magneto to coil ignition. This involved squeezing a pair of coils into the magneto body along with some electronics. I have tested the magneto on a car (Morgan 3 wheeler) and the results are very encouraging.

This is very much a prototype, and I am beginning to think about longer term testing and a version 2 with some improved weather protection. I have replaced the original magneto bearings with standard sealed bearings, but I would like something outboard of the sealed bearing to keep water (rain – the magneto is very exposed on the front of the car) out of the magneto body. I thought about a lip seal but wondered about how it would manage with no lubrication? In dry weather it would be running dry. An option might be to remove the seal on the bearing on the lip seal side anticipating some grease from the bearing lubricating the seal.

Does anyone have any recommendations for this application? Probably looking at 3000 rpm, shaft diameter 15mm.

Thanks

Ian

The mag will be lucky to see 3000 rpm on this sidevalve, and would most likely only see it momentarily before something catastrophic happened 😬, but some or the more exciting ohv engines will rev up to 6000 rpm and even a bit beyond. A rev limiter can be programmed into the mag if required to look after the engine.

The electronic mag is designed to run clockwise or anti-clockwise, and by changing the discrete timing board mounted in a dummy cam ring, it can handle different engine types with different V angles.

There are plenty of magnetos around where the defunct magneto becomes simply a housing for a set of points. You then you have coils, or a double ended coil tucked away somewhere under the bonnet. The original magneto HT leads are either removed or tucked away somewhere, and the working HT leads from the coil(s) emerge from under the bonnet. This works but loses something in terms of authenticity.

The objective of this project was to develop a magneto that was indistinguishable from the original instrument. This means that the magneto HT leads must be real. The unit must be completely self contained, there can be nothing mounted remotely, and you can only have one wire (the original only has an earth wire) going to the magneto. The original cable advance/retard control must operate as normal. An extra rule I added in was that the double ended coil/wasted spark approach would not be used – it has been associated with carb fires on these engines.

So we have two separate coils inside the magneto body, the secondaries essentially hard wired to the HT pickups – so no distributor and no carbon brushes. There is also a PC board tucked away inside the magneto body with two more or less independent ignition circuits. A relatively small diameter shaft driven by the standard bevel gear passes between the coils and through a hole in the centre of the main PC board. The shaft terminates in the points housing.

The single wire is used to provide 12 volts from the ignition circuit.

Inside the points housing is a dummy cam ring which provides a mounting for the trigger PC board. The manual advance retard control engages with the dummy cam ring in the normal way. The trigger board provides mounting for two Hall sensors, one for each circuit. Each sensor has an associated LED indicator light to allow you to time the magneto. The Hall sensors are mounted on the PC board, separated by an angle chosen to suit the V angle of the engine. On the end of the shaft is a taper on which is mounted a component with a ring magnet that presents N and S poles to the Hall sensors.

To time the magneto, you mount it on the engine without worrying about timing, you just engage the bevel gears. You set the manual adv/retard to max advance and then turn the engine to the appropriate firing point for No 1 cylinder. You then rotate the ring magnet until it just fires No 1 (the LED indicator facilitates this). You nip the ring magnet holder up on its taper, fit the cover and then drive off 😃.

Happy to have a chat about your set up – send me a pm If you would like to have a natter.

Ian

There is a cover for the bevel gears and oil pump drive, here is a close up. You can also see the mag end cover in place.

Here is the contact breaker housing with the Luminition through beam units installed. The 4 core cable heads off to the control unit under the bonnet and the coils.