IGNITION SYSTEMS Flashcards
What is a magneto?
A magneto is a special type of engine-driven AC generator that uses a permanent magnet as a
source of energy. The magneto develops a high voltage that is used to fire the spark plugs.
What is the purpose of the condenser in a high-tension magneto electrical system?
To prevent arcing at the points and to hasten the collapse of the magnetic field around the
primary coil.
Where is the E-gap position in a magneto?
The E-gap position is when the poles of the rotating magnet are a few degrees past the neutral
position.
What are the three major circuits of a high-tension magneto system?
The magnetic circuit, the primary electrical circuit, and the secondary electrical circuit
What are the components of a high tension magnetic circuit?
The magnetic circuit consists of a permanent multipole rotating magnet, a soft iron core, and
pole shoes.
What happens when the primary breaker points open in a magneto?
Opening the breaker points, stops the flow of current in the primary coil. The magnetic field that
was emitted by the primary coil collapses. As this magnetic field collapses, its flux lines cut
across the windings of the secondary coil, inducing the pulse of high voltage current in the
secondary coil needed to fire the spark plugs.
. What is the piston position when the spark occurs in a cylinder?
The piston is a specified number of crankshaft degrees before top dead center of the
compression stroke.
What is a dual magneto ignition system?
The duel magneto system incorporates two magnetos in one housing, and one rotating magnet,
and a cam are common to two sets of breaker points and coils. On radial engines, the right
magneto fires all the front plugs and the left magneto fires all the rear plugs.
What is the difference between a low-tension and a high-tension ignition system?
In the high-tension system, high voltage is generated in the magneto and flows to the plugs
through high-tension leads. In a low-tension system, low voltage is generated in the magneto
and flows through low-tension leads to the primary winding of a transformer coil located near
each spark plug. There the voltage is increased to high voltage by transformer action and is
conducted to the plugs by very short high-tension leads.
When the ignition switch is in the OFF position, what is the condition of the primary circuit?
It is completed through the ignition switch to ground.
What three conditions are required to fire plugs in a cylinder when the piston is in the prescribed position?
The magneto’s magnet poles must be in the E-gap position, the breaker points must open, and
the distributor rotor must be aligned with the distributor electrode for that cylinder.
In a dual magneto ignition system, what part of the system is grounded when the ignition switch is placed in
the RIGHT position?
The left magneto circuit will be grounded.
What is internal timing of a magneto?
It is adjusting the breaker points to open when the poles of the rotating magnet are at the E-gap
position.
What is the purpose of an impulse coupling used with a magneto?
The purpose of an impulse coupling is to retard the timing of the spark for starting the engine,
and then spin the magneto rapidly to produce a hotter spark.
What is staggered ignition timing?
It is the firing of one spark plug before the other one instead of firing them simultaneously
