Re: How do Atom Computer Ignition modules work?

[legendre]

@debe & VinTin

Then all three of us are in agreement. In this type of magneto, the flywheel magnets & pole shoes are arranged to provide the maximum spark energy at or near the angle where the ignition event should be set to occur. When the ignition timing is correctly set (in terms of angle relative to TDC), the ignition event (points break) will roughly coincide with the angle of maximum spark energy.

They don’t always perfectly coincide, as the manufacturing just isn’t that precise – nor does it need to be. If we’re off the max peak by a couple of degrees either direction, we’ve still got ~90% or so of max energy, and plenty to generate sufficiently powerful spark. Properly timing the ignition event relative to TDC is the more critical tuning parameter.

The situation is different with an accessory magneto, like a Lucas, or other engine-driven accessory mag. On those systems, you can set the point gap to fire the mag precisely at the magnetic peak – and then the entire mag can be timed to the engine, as it’s driven by a gearwheel that sits on an un-keyed taper. You can set your perfectly-timed mag to fire at any crankshaft angle by changing the position of the drive gear- best of both worlds.