d. Inspection and test.
(1) Inspect field coils for worn or frayed
(1) Turn commutator on lathe, if more than 0.002
insulation; corroded, loose or burned terminal stud
inch out of round, burned, or if mica projects above 88
assembly; and loose and/or corroded connections.
commutator copper segments. Do not undercut mica
(2) Inspect brushes for excessive wear and oil
saturation and brush springs for corrosion and lost
(2) If burned contact disc can be cleaned up
without removal of much metal, clean by filing to bright
(3) Using .lamp and two probes, test armature
for ground. Place one probe on commutator and the
f. Assembly. Reverse b above.
other probe on the laminated core. If test lamp lights,
armature is grounded. Replace it.
g. Installation. Reverse a above.
(4) Using growler, test armature circuits. If
shorted circuit is discovered, clean between all bars of
commutator; then retest. If open circuit is indicated,
(1) Loosen screw at distributor primary terminal
(5) Replace defective items.
and remove primary circuit lead-in wire.
(6) Inspect brushes for excessive wear (beyond
(2) Snap clips from distributor cap and lift cap
one-half the length of a new brush), and loose or frayed
from distributor. Do not remove wires from cap.
brush leads. Replace defective brushes with new ones.
Sand new brushes with No. 00 sandpaper. Hold
(3) Chalk mark edge of distributor to indicate
sandpaper against commutator, grit side against brush,
location of rotor tip before removal, loosen clamp screw
and pull sandpaper so that the brush is drawn to the
and lift out distributor.
brush arm. As brush is sanded, it assumes the contour
Do not turn engine crankshaft until
(7) Springs. Inspect springs for wear, rust, or
distributor is reinstalled.
corrosion, loss of tension, and evidence of overheating.
Springs should hold brushes firmly against commutator.
Replace defective springs with new ones.
(1) Remove distributor cap and rotor. Remove
(8) Field frame.
seal from distributor body.
(a) Using a test light, check field frame, field coils,
(2) Disconnect lead from contact set and remove
and terminal studs for ground. Hold one test probe on
contact set and condenser.
the terminal stud and the other test probe on the field
frame. If lamp lights, a ground is present. To locate the
(3) Remove breaker plate. Remove centrifugal
ground, remove terminal stud and field coil lead from
advance springs carefully.
frame. Place one test probe on terminal stud and other
test probe on field frame. If lamp fails to light, ground is
between terminal stud and field frame. If lamp does
The tension of these springs is
light, ground is between field coils and pole shoes on
calibrated to control the automatic
spark advance mechanism.
must not be stretched or distorted, or
(b) Using same test light, test field coils for open
engine performance will be affected.
circuit by placing one test probe on each of leads coming
Lift advance weights from pivots on
from the field coils. If lamp lights, no open circuit is
present. If lamp does not light, an open circuit is
(4) File or grind off peened overhead of pin and drive out
pin. Remove gear, shims and washer, then take shaft
from distributor body.