In what position is the magnet in a magneto when the breaker points begin to open?

In what position is the magnet in a magneto when the breaker points begin to open?

• A. Neutral position
• B. E-gap position just beyond neutral
• C. A few degrees before neutral
• D. Maximum flux density

Answer: (B)

In a magneto, the spark is produced when the breaker points open, interrupting the current in the primary winding and letting the magnetic field collapse to induce a high-voltage pulse. The cam that drives the breaker points defines a reference position called the E-gap. As the cam rotates past neutral, the points begin to separate at the E-gap position. This is the exact moment the timing is set to begin opening so the spark occurs at the correct crank angle for the engine. So the magnet is in the E-gap position just beyond neutral when the breaker points begin to open. Opening at other positions would mis-time the spark, and maximum flux density isn’t the moment the points start to open.

In a magneto, the spark is produced when the breaker points open, interrupting the current in the primary winding and letting the magnetic field collapse to induce a high-voltage pulse. The cam that drives the breaker points defines a reference position called the E-gap. As the cam rotates past neutral, the points begin to separate at the E-gap position. This is the exact moment the timing is set to begin opening so the spark occurs at the correct crank angle for the engine. So the magnet is in the E-gap position just beyond neutral when the breaker points begin to open. Opening at other positions would mis-time the spark, and maximum flux density isn’t the moment the points start to open.