FAA Powerplant Written Practice Test

What does the E-gap angle represent in a magneto system?

1. The angle between the magnet and the distributor

2. The angle between the magnet's neutral position and when the contact points open

3. The angle at which the primary coil is activated

4. The angle of the crankshaft during ignition

The correct answer is: The angle between the magnet's neutral position and when the contact points open

The E-gap angle in a magneto system specifically refers to the angle between the magnet's neutral position and the position at which the contact points open. This angle is crucial for the proper timing of ignition in reciprocating engines. When the magnet moves, it generates a magnetic field that interacts with the primary coil of the ignition system. The contact points must open at a precise moment to ensure that the magnetic field is at its peak when the coil starts to collapse, allowing for the maximum generation of voltage in the secondary coil and consequently creating a strong spark at the spark plug. Understanding the E-gap angle is essential for maintaining proper ignition timing, which directly impacts engine performance and efficiency.