FIG. 2 Advance Mechanisms - Dual Advance Distributor with Single Diaphragm
FIG 3 Typical Conventional Ignition System Circuits
When the breaker points are closed. current flows
High voltage is produced each time the breaker points
from the battery through the ignition switch to the primary
open. The high voltage flows through the coil high tension
windings in the coil, then to ground through the closed breaker
lead to the distributor cap where the rotor distributes it to one
points. When the breaker points open, the magnetic field built
of the spark plug terminals in the distributor cap. This process
up in the primary windings of the coil moves through the
is repeated for every power stroke of the engine.
secondary windings of the coil, producing high voltage.
fuel tank and that fuel is reaching the carburetor. Then locate
DIAGNOSIS AND TESTING
Ignition systems troubles are caused by a failure in
spark intensity test.
the primary and/or secondary circuit; incorrect ignition timing;
or incorrect distributor advance. Circuit failures may be
SPARK INTENSITY TESTS
caused by shorts, corroded or dirty terminals, loose
connections, defective wire insulation, cracked distributor cap
or rotor, defective distributor points, fouled spark plugs, or by
1. Connect an auxiliary starter switch in the starting
improper dwell angle.
If engine starting or operating trouble is attributed to
2. Remove the coil high tension lead from the distributor
the ignition system, start the engine and verify the complaint.
On engines that will not start, be sure there is gasoline in the
3. Turn on the ignition switch.