Ignition System
Part 2 Ignition System
COMPONENT INDEX
Page
COMPONENT INDEX
Page
IDENTIFICATION ............................................
REMOVAL AND INSTALLATION.................
DESCRIPTION ................................................
Breaker Pints and/or
DIAGNOSIS AND TESTING ...........................
Condenser ........................................
Spark Intensity Tests.................................
Spark Plug Wire ......................................
Ignition System Tests ................................
Spark Plugs .............................................
Distributor Tests - On Vehicle ...................
Vacuum Advance Unit.............................
Distributor Tests - Off Vehicle ...................
Breaker Plate and Sub-Plate...................
ADJUSTMENTS ..............................................
Cam and Centrifugal Advance ................
Centrifugal Advance ..................................
Weights ............................................
Vacuum Advance ......................................
Distributor ................................................
Breaker Points and/or
CLEANING AND INSPECTION ...................
Condenser ..........................................
Spark Plugs .............................................
Ignition Timing ...........................................
Distributor ................................................
IDENTIFICATION
The distributor identification number is stamped on
the distributor housing. The basic part number for distributors
is 12100/ To procure replacement parts, it is necessary to
know the part number prefix and suffix (Figure 1).
Always refer to the Parts Catalog for parts usage and
interchangeability before replacing a distributor or a
component part for a distributor.
FIG. 1 Distributor Identification
positioned on the opposite side of the cam from the pivot pin,
DESCRIPTION
then moves opposite to distributor rotation and advances the
spark timing. As the movable breaker plate is rotated from
The distributor is located on the right side of the
retard position to full-advance position, the breaker point dwell
engine. It is equipped with both a vacuum and a centrifugal
will remain constant due to the breaker point rubbing block and
advance unit to control ignition timing. The vacuum advance
the cam rotating on the same axes of the new design breaker
governs the ignition timing (spark advance) during low engine
plate and sub-plate.
speeds (rpm) or low engine loading. The centrifugal advance,
in combination with the vacuum advance, controls the ignition
CONVENTIONAL IGNITION SYSTEM
timing at higher engine speeds or heavy engine loads to
The ignition system consists of a primary (low
provide the correct ignition timing for maximum engine
voltage) and a secondary (high voltage) circuit (Figure 3).
Performance.
The primary consists of the:
1
Battery.
VACUUM SINGLE ADVANCE UNIT
2
Ignition switch.
3
Primary circuit resistance wire.
The distributor advance systems are independently
4
Primary windings of the ignition coil.
operated. The centrifugal advance mechanism (Figure 2),
5
Breaker points.
located below the stationary sub-plate assembly, has
6
Condenser.
centrifugal weights that move inward or outward with changes
The secondary circuit consists of the:
in engine speed. As engine speed increases the centrifugal
1
Secondary windings of the ignition coil.
weights move ahead with respect to the distributor drive shaft.
2
Distributor rotor.
The rate of advance is controlled by calibrated weight springs.
3
Distributor cap.
The vacuum single advance has a spring loaded
4
High tension wires.
diaphragm connected to the breaker plate assembly. The
5
Spark plugs.
diaphragm is moved against the spring pressure by vacuum
pressures. When the vacuum increases, the diaphragm
causes the movable breaker plate to pivot on the stationary
sub-plate.
The breaker point rubbing block, which is
2-01
