Question 3
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List two methods of controlling ignition timing.
(b) Briefly describe the operation of contact breakers in ignition systems.
(c) Fig. 1 is a schematic layout of coil ignition system of a four-cylinder engine arrangement.
Name the parts labelled A, B, C, D, E, F, G and H.
Observation
The expected responses were:
- Methods of controlling ignition timing
- Advancing the ignition
- Retarding the ignition
- Operation of contact breaker in ignition systems
- When the ignition switch is turned ON, current flows from the primary windings of the coil to contact breaker points.
- Cranking of the engine in turn causes rotation of the cam lobe in the distributor.
- The rotation of cam lobes in turn causes opening and closing of the contact breaker gap.
- When the contact breaker is opened, current flows in the primary circuit breaks thus the current is returned into the secondary windings of the coil.
- The secondary windings of the coil increased greatly into value high enough to cause spark at the spark plugs.
- Parts of a coil ignition system
A – Earth
B – Battery
C – Switch
D – Coil
E – Contact breaker
F – Capacitor/condenser
G – Spark plugs
H – Distributor cap