| Symptom | Probable Cause | Solution | | :--- | :--- | :--- | | | Broken impulse coupling (no "snap" sound). | Replace impulse coupling. | | | P-Lead grounded (Switch in OFF position). | Check wiring/key switch. | | | Wet points (oil contamination). | Clean or replace points. | | Hard starting (Hot) | Timing drifted. | Re-time magneto. | | | "Vapor lock" (fuel issue, not mag). | Prime/throttle management. | | Rough running at speed | Broken ground wire (P-lead). | Inspect wires for chafing. | | | Cracked distributor block. | Inspect block for carbon tracking/cracks. | | High RPM Drop on check | Fouled spark plug. | Clean/replace plugs. | | | Magneto timing retarded. | Re-time the magneto. |
Original paper manuals are frequently found on eBay , while digital archives like the AirCorps Library host historical technical data for older models like the DF and SF series. scintilla magneto manual
A magneto is a self-contained high-voltage generator. Unlike a battery-and-coil system, a magneto requires no external battery. It uses permanent magnets and a induction coil to create a spark exactly when the piston reaches compression. | Symptom | Probable Cause | Solution |
With rotor installed at #1 firing position, the manual instructs to loosen the coil hold-down screws and slide the coil until a 0.004" feeler gauge fits between the rotor magnet and the coil pole. Tighten, then confirm points just begin to open at that rotor position. | Check wiring/key switch
Before diving into the manual, understanding the manufacturer is crucial. Scintilla AG was founded in Switzerland in 1917. They became world-renowned for their magneto ignition systems used on high-speed internal combustion engines. Unlike battery-coil systems that rely on a charged battery, magnetos generate their own power using permanent magnets and induction coils. This makes them reliable in remote locations—hence their use on farm tractors (Ford, Ferguson), military generators, and aircraft (such as the de Havilland Mosquito).
If the points are pitted or "frosted," they should be replaced or dressed with a fine point file. 4. Internal Timing (The E-Gap)