Buick LeSabre 1965 Service Manual page 613

ELECTRICAL SYSTEMS
DISTRIBUTOR SERVICE 1 0 - 4 3
the life of contact points will be
improved by installing a conden-
ser of high-limit capacity if metal
build-up is on breaker arm point,
or a condenser of low-limit capa-
city if metal build-up is on con-
tact support point. There is
usually sufficient variation in the
capacities of stock condensers to
permit selection of a high or low
limit condenser by testing the
available stock.
c. Low Insulation Resistance
A weak or leaking condenser is
usually one that has absorbed wa-
ter so that the insulation resist-
ance of the winding is lowered
to the extent that the condenser
will not hold a charge satisfac-
torily. A condenser with low in-
sulation resistance will drain
sufficient energy from the ignition
system to lower the secondary
voltage seriously. The condenser
specified for use in the Buick
ignition system is sealed to pre-
vent absorption of water, and nc
other type should be used.
A leaky condenser usually does
not affect engine performance ex-
cept when hot. It is unlikely that
a condenser with low insulation
resistance would cause missing
at low or medium speeds under
conditions where the condenser
does not get hot. A condenser
that has low enough resistance to
affect engine performance when
cold would probably be indicated
as broken down on most conden-
ser testers.
Condenser testers equipped to
check condensers for low insula-
tion resistance usually give a
reading in megohms, a megohm
being one million ohms. The scale
is marked to indicate whether the
condenser is good or bad.
When testing a condenser for low
insulation resistance the l e a d
should always be disconnected
from the distributor. Since the
distributor terminals and the con-
nected circuit have much lower
insulation resistance than the
condenser, failure to disconnect
the condenser lead will give a
reading much too low.
1 0 - 3 9 DISTRIBUTOR SERVICE
OPERATIONS
a. Removal and Disassembly of
Distributor for Inspection
1. Disconnect the distributor pri-
mary wire from coil and discon-
nect hose from vacuum unit.
Remove distributor cap by insert-
ing a screwdriver in upper slotted
end of cap latches; then press
down and turn 90° counterclock-
wise.
2. Make a mark on distributor
base in line with center of rotor.
Then carefully note the direction
the vacuum unit points in relation
to the engine so that the distrib-
utor can be replaced in the exact
same position after it is serv-
iced. See Figure 10-44 or 10-45.
CAUTION: If engine is turned
over while distributor is out,
complete ignition timing proce-
dure must be followed (par.
10-33).
3. Remove distributor clamp and
lift distributor out of crankcase.
4. Remove rotor from end of dis-
tributor shaft by removing two
a t t a c h i n g s c r e w s and lock
washers.
5. Remove contact point set and
condenser as described in para-
graph 10-34.
6. Remove two screws holding
vacuum advance unit to housing.
Remove advance unit.
7. Remove "O" ring seal from
shaft housing.
b. Inspection of Distributor
Parts
1. Wash the distributor assem-
bly in clean solvent, holding hous-
ing horizontal to avoid getting
cleaning solvent into the lubricant
reservoir. Dry parts thoroughly.
2. Cap. Wipe out distributor cap
with a clean cloth and inspect it
for chips, cracks, and carbonized
paths which would allow high-
tension leakage to ground. Such
defects require replacement of
cap. Clean loose corrosion from
surfaces of terminal segments in-
side the cap. Do not use emery
cloth or sand paper. If segments
are deeply grooved, the cap should
be replaced. Pull cables from
terminal sockets and i n s p e c t
sockets for corrosion. Clean
sockets, using a stiff wire brush
to loosen corrosion.
3. Rotor. If rotor is cracked,
spring contact is badly worn, or
rotor tip is badly burned, rotor
must be replaced.
4. Condenser. Inspect condenser
and primary leads for loose or
frayed t e r m i n a l connections.
Check condenser in a reliable
condenser tester as described in
paragraph 10-38.
5. Vacuum Advance Unit. Inspect
rod end for excessive wear. Push
rod into unit as far as possible,
hold finger tightly over nipple
and then release rod. After about
15 seconds, release finger from
hole and notice if air is drawn in.
If not, diaphragm is leaking and
unit must be replaced.
6. Contact Ponts. Carefully ex-
amine the mating surfaces of the
contact points, noting whether
they are flat and making good
contact, or whether they are
blackened, pitted, burned, or
worn excessively. Contact points
which have been in service for
some time will appear dull and
gray. This condition is normal
and such points should not be
replaced.
Contact points which are black-
ened or only slightly burned or
pitted may be cleaned with a thin
contact stone or a clean fine-cut
contact file. Remove high points
only; it is not necessary to remove