fuel JEEP DJ 1953 Repair Manual

'Jeep'
UNIVERSAL
SERIES
SERVICE
MANUAL

F2

14043

FIG.
F2-6—REPLACING VACUUM MOTOR ASSEMBLY

A—Drill
VW
Hole
B—Sensor
Unit
Replacement Position
1—
Motor
3—Sensor
Unit

2—
Spot
Welds
4—Retaining
Strap
•e.
Drill
a
%j
inch [2,78 mm.] hole in snorkel tube

at
point
"A"
as shown in Fig.
F2-6.
f.
Use the motor strap retainer and the
sheet
metal

screw
provided in the motor replacement kit to secure the retainer and motor to the snorkel tube.
g. Make sure the screw
does
not interfere with the
operation of the damper assembly. Shorten screw
if
required.

F2-9.
Replacement
of Air
Cleaner Sensor

a.
Remove two sensor retaining clips by
prying.
See

Fig.
F2-7.

b.
Pull
vacuum
hoses
from sensor.

c.
Note
carefully the installed position of the sensor so that you can install new sensor in same position.

Then
remove sensor.

d.
Install
sensor and gasket assembly in air cleaner

m
same position as noted in
step
c.
This
is to eliminate the possibility of interference with the air

filter
element.
e.
Install
sensor retaining
clip,
meanwhile support­
ing
sensor at B around the outside rim to prevent 14042

FIG.
F2-7—REPLACING SENSOR ASSEMBLY

1—Sensor
Retaining
Clip
damage to the temperature sensing spring. See

Fig.
F2-7.

f.
Reinstall
vacuum hoses.

F2-10.
AIR
PUMP
The
air injection pump is a positive displacement
vane type which is permanently lubricated and
requires
no periodic maintenance.

The
pump contains an integral relief valve which
controls the
air
supplied to the
engine
exhaust ports

during
high speed operation to limit maximum exhaust system temperatures.

F2-11.
AIR
FILTER
The
air injection system draws clean air from the
carburetor
air filter through an inlet hose, into the

air
pump and from the pump through two
outlets
(one for each cylinder head).

F2-12.
AIR
DELIVERY MANIFOLD

The
air delivery manifolds constructed of cold
rolled
steel with a zinc plating, distribute the air

from
the pump to each of the air delivery tubes in

a
uniform manner.

Two
check valves are included to prevent the
reverse
flow of exhaust
gases
to the pump should
the pump drive
fail.
This
reverse flow would dam­
age the air pump and connecting hose.

F2-13.
AIR
INJECTION TUBES
The
air injection tubes of stainless steel are in­ serted into machined
bosses
of the cylinder head.

The
tubes project into the exhaust ports directing
air
into the vicinity of the exhaust valve stem.

F2-14.
ANTI-BACKFIRE VALVE
The
anti-backfire valve is used to provide a "gulp" of air into the
engine
induction system during
rapid

throttle opening and subsequent closure.
During
rapid
throttle closure, the valve
opens
for approxi­
mately one (1) second and bleeds air into the
intake
manifold through a fitting in the carburetor.

Its
function is to bleed an adequate amount of

air
below the carburetor throttle plate to compen­ sate for the
overrich
fuel mixture normally inducted
into the combustion chamber during
rapid
throttle

closure.

Filtered
air from the pump is provided to the
anti-backfire
valve by means of a connecting hose.

An
exhaust system backfire
will
result if the valve

fails
to function properly.

F2-15.
ENGINE COMPONENTS
The
following item varies in design or specifications

from
those
on vehicles not equipped with the Ex­

haust
Emission
Control
System.

F2-16.
Carburetor

Check
carburetor number for proper application. Specifications are listed in this section.

Proper
carburetor idle mixture adjustment is im­ perative for
best
exhaust emission control.

The
idle adjustment should be made with the en­
gine
at normal operating temperature, lights and accessories off and the air cleaner in place.
Adjust
155

F2
EXHAUST EMISSION CONTROL SYSTEMS
the throttle
stop
screw to idle the
engine
at 650
to 700 rpm.

F2-17. Carburetor Idle Setting
The
"Lean
Best
Idle"
Method of Idle Setting is as
follows:

a.
Any scheduled service of ignition system should
precede this adjustment

b.
Connect tachometer to engine.

c.
Warm
up
engine
and stabilize temperatures.

d.
Adjust
engine
idle to speed desired, using throt­
tle idle speed adjusting screw.
e.
Turn
idle mixture screws out (counterclockwise)

until
a
loss
of
engine
speed is indicated; then slowly
turn
mixture screws in (clockwise-leaner)
until
maximum speed (rpm) is reached. Continue

turning
in (clockwise) until speed begins to drop;

turn
mixture adjustment back out (counterclock­
wise-richer)
until maximum speed is just regained

at
a "lean as possible" mixture adjustment.

F2-18. Distributor
The
ignition distributor used with the
Exhaust
Emission
Control
System is the same as that used
on
engines
without
Exhaust
Emission
Control.
Check
the distributor cam dwell angle and point
condition.
Check
ignition timing and adjust to specifications shown on the last
page
of this section.

F2-19.
Anti-Backfire
Valve

The
anti-backfire valve remains closed except when
the throttle is closed rapidly from an open position.
To
check the valve for proper operation, accelerate
the
engine
in neutral, allowing the throttle to close

rapidly.
The valve is operating satisfactorily when
no exhaust system backfire occurs. A further check
to determine whether the valve is functioning can
be made by removing from the anti-backfire valve
the large
hose
which connects the valve to the

pump.
With
a finger placed over the open end of
the
hose
(not the valve), accelerate the
engine
and allow the throttle to close rapidly. The valve is
operating satisfactorily if a momentary air rushing
noise is audible.

F2-20.
Check
Valve

The
check valves in the lines to the air distribution manifolds prevent the reverse flow of exhaust
gases

to the pump in the event the pump should, for

any
reason,
become
inoperative or should exhaust

pressure
ever exceed pump pressure.

To
check this valve for proper operation, remove the air supply
hose
from the pump at the check

valve.
With
the
engine
running, listen for exhaust
leakage at the check valve which is connected to
the distribution manifold.

F2-21.
Air
Pump

Check
for proper drive belt tension with belt tension
gauge
W-283. The belt strand tension should be 60 pounds measured on the
longest
accessible span
between two pulleys. DO NOT PRY ON THE

DIE
CAST
PUMP
HOUSING. To
check the pump for proper operation, remove
the air
outlet
hose
at the pump.
With
the
engine

running,
air discharge should be felt at one of
the pump
outlet
openings. The pump
outlet
air
pressure,
as determined by the relief valve, is preset
and
is not adjustable.

The
air pump
rear
cover assembly, housing the pressed in inlet and discharge tubes, and the pres­
sure
relief valve are the only pump components
recommended for service replacement. These parts
are
to be replaced only when damaged as a result
of handling or in the event the relief valve was
tampered with.

F2-22.
Intake Manifold

Intake
manifold leaks must not be overlooked. Air
leakage at the intake manifold may be compen­
sated for by
richer
idle mixture setting, however, this
will
usually cause uneven fuel-air distribution
and
will
always result in
loss
of performance and
exhaust emission control. To check for air leakage
into the intake manifold, apply kerosene or naph­
tha,
on the intake manifold to cylinder head joints

and
observe whether any changes in
engine
rpm

occur.
If an air leak is indicated, check the mani­
fold to cylinder head bolt torque. The correct torque is 25-35 lbs. ft. [3,46 a 4,84 kg-m.]. If the

leak
is
still
evident,
loosen
the manifold assembly

and
torque-tighten the bolts evenly.
Start
from the center and use proper torque values. Replace the
manifold
gasket if the leak
still
exists.
Clean
both
mating surfaces and check for
burrs
or other ir­

regularities.

Always
torque the bolts evenly to the specified
torque value to prevent warpage.

F2-23.
Carburetor
Air
Cleaner
—Oil
Bath

Every
6,000
miles [9,600 km.] disconnect attach­

ing
hoses
and unscrew the wing nut from the top
of the air cleaner and lift it off the carburetor.

Lift
the cover and filter element off the oil sump.

Clean
the inside surface of the sump and
refill
to

indicated
oil level with SAE 40 or 50
engine
oil
above 32 F; SAE 20 below 32 F.
Wash
filter element in kerosene and
drain.
Reassemble the air

cleaner
and install on carburetor.

More
frequent cleaning and replacement are advis­ able when the car is operated in dusty areas or on

unpaved
roads. Accumulated
dirt
restricts air flow,
reducing
fuel economy and performance.

F2-24.
REMOVAL PROCEDURES
The
following paragraphs
give
the procedures for removing the major units of the exhaust emission
control
system and the required equipment needed.

F2-2S.
Air
Pump

Loosen
the air pump mounting bracket bolts. Re­ move the air pump air hose(s). Separate the air pump from its mounting bracket. At time of install­
ation,
torque tighten the air pump mounting bolts
to
30-40
lbs.-ft [4,15 a 5,53 kg-m.].
Adjust
the
belt strand tension to 60 pounds. 156

'Jeep'
UNIVERSAL
SERIES
SERVICE
MANUAL

H
11514

FIG.
H-2—WIRING
DIAGRAM—MODEL
CJ-3B
(Serial No.
35522
and
after)

1—
Left
Headlamp
2—
Left
Parking and Signal Lamp
3— Right Parking and Signal Lamp
4— Right Headlamp 5— Battery Ground Strap
6— Generator 7— Ignition
Coil

8— Junction Block
9—
Horn

10— Distributor
11— Battery
12—
Voltage
Regulator 13— Starting Motor
14—
Oil
Pressure Signal Switch 15— Temperature Sending Unit
16—
Solenoid
Switch 17— Foot Dimmer Switch
18—
Stop
Light Switch 19— Directional Signal Flasher
20— Fuse
21—
Light
Switch 22— Directional Signal Switch
23—
Horn
Button 24— Ignition and Starter Switch 25—Instrument Cluster
A—Upper Beam Indicator
B—Turn
Signal Indicator C—Instrument Lights

D—Oil
Pressure Indicator
E—Charging
Indicator F—Temperature Gauge

G—Fuel
Gauge
H—Instrument
Voltage
Regulator
25—Fuel Gauge Tank Unit
27—
Left
Tail
and
Stop
Lamp
28— Right
Tail
and
Stop
Lamp 175

H

ELECTRICAL
SYSTEM
11474

FIG.
H-3—WIRING
DIAGRAM—MODELS
CJ-5, CJ-6, DJ-5 AND DJ-6—F4
ENGINE
(Model CJ-5 after Serial No.
49248,
Model CJ-6 after Serial No.
12577)

1—
Left
Headlamp
B—Turn
Signal Indicator 17—Directional Signal Switch
2—
Left
Parking and Directional Lamp C—Instrument Lights 18—Light Switch
3— Right Parking and Directional Lamp
D—Oil
Pressure Indicator
19—Stop
Light Switch
4— Right Headlamp E—Charging Indicator 20—Foot Dimmer Switch
5— Battery Ground Cable F—Temperature Gauge 21—Directional Signal Flasher
6— Generator
G—Fuel
Gauge 22—Fuse 7— Distributor H—Instrument Voltage Regulator
23—Solenoid
Switch
8— Ignition
Coil
12—Right
Tail
and
Stop
Lamp 24—Temperature Sending Unit
9— Starting Motor 13—Left
Tail
and
Stop
Lamp 25—Oil Pressure Signal Switch
10— Voltage Regulator 14—Fuel Gauge
Tank
Unit 26—Horn
11— Instrument Cluster 15—Ignition and Starter Switch 27—Junction Block
A—Upper
Beam Indicator 16—Horn Button
whereas the Dauntless V-6
engine
Delco starter
ignition
switch. If trouble
develops
in this switch, drive is of the clutch
type.
it must be replaced.
The
ignition
switch
serves
both
to
energize
the

The
starter circuit is
opened
when the
ignition
key
ignition
system
and
also
to
engage
the starter
sole-

is allowed to return to the "Ignition On"
position.
miod switch. With the key in the vertical
position,
No repairs or adjustments can be
made
to the the electrical
system
is off. This is the
only
position
176

'Jeep*
UNIVERSAL
SERIES
SERVICE
MANUAL

H

12968
FIG.
H-4—WIRING
DIAGRAM—MODELS
CJ-5, CJ-6, DJ-5, DJ-6
LATE
F4
ENGINE

1—
Left
Headlamp
2—
Left
Parking and Signal Lamp
3— Right Parking and Signal Lamp 4— Right Headlamp
5— Generator
6— Ignition Distributor
7—
Oil
Pressure Sending Unit
8— Junction Block
9—
Horn

10— Foot Dimmer Switch 11—
Stop
Light Switch — Front
12— Temperature Sending Unit
13— Ignition
Coil

14— Starting Motor 15— Battery Ground Cable
16— Battery
17— Voltage Regulator 18—
Fuse

19— Instrument Cluster

A—Hi-Beam
Indicator

B—Auxiliary
C—Instrument
Lights

D—Oil
Pressure Indicator
E—Charging
Indicator
F—Temperature
Indicator

G—Fuel
Gauge
H—Instrument Voltage Regulator
20— Ignition and Starter Switch 21—
Flashei
(Directional Signal)
22—
Horn
Button 23— Directional Signal Switch
24— 4-Way Flasher Switch
25—
Flasher
(4-Way)
26—
Fuse

27—
Main
Light Switch 28—
Stop
Light Switch — Rear
29—
Fuel
Gauge
Tank
Unit
30—
Back-Up
Light Switch
31— Right
Tail
and
Stop
Lamp
32— Right Back-Up Lamp
33—
Left
Back-Up Lamp
34—
Left
Tail
and
Stop
Lamp

in
which the key can be removed. Turning the key
to the
left
energizes
auxiliary
equipment
such as
windshield wipers, radio, and heater. The turn
signal
lights
will
operate
with the
ignition
key in
either the
left
or right
position.
The
ignition
switch is held in
position
by a
tension
spring on the back
of the instrument panel and a
notched
bezel on
the front of the instrument panel.
H-8.
Lighting System

The
wiring for the lighting
system
is shown in the
wiring diagrams, Figs. H-2 thru H-7 of the manual,
which indicate the various units in relation to their

position
in the vehicle. The lighting circuit is pro­
tected
by an overload circuit breaker
mounted
on the rear of the light switch.
The
main light switch controls the lighting
system
177

H

ELECTRICAL
SYSTEM

14365

FIG.
H-5—WIRING
DIAGRAM—F4
ENGINE
CURRENT
MODEL
1—
Left
Headlamp

2—
Left
Parking and Signal Lamp
3—
Right
Parking and Signal Lamp

4—
Right
Headlamp
5—
Marker
Lamp
— Amber
6—
Generator
7—
Distributor

8—
Ignition
Coil

9— Starting Motor
10— Battery Ground Cable
11—
12
Volt
Battery

12—
Flasher
(Directional Signal)
13— Instrument Cluster
A—Hi-Beam
Indicator

B—Auxiliary
C—Instrument Lights
D—Oil
Pressure
Indicator
E—Charging Indicator
F—Temperature Indicator
G—Fuel
Gauge
Indicator
H—Instrument Voltage Regulator
14—
Ignition
and
Starter
Switch
15—
Horn
Button 16—
Directional
Signal Switch 17— 4-Way
Flasher
Switch
18—
Flasher
(4-Way)
19—
Windshield
Wiper Motor Switch
20—
Main
Light
Switch

21—
Fuel
Gauge
Tank
Unit

22—
Back-Up
Light
Switch
23—
Marker
Lamp — Red 24—
Right
Tail
and Stop Lamp
25—
Right
Back-Up Lamp
26—
Left
Back-Up Lamp
27—
Right
Tail
and Stop Lamp
28—
Marker
Lamp — Red 29— Stop
Light
Switch
30— Foot Dimmer Switch

31—
Windshield
Wiper Motor Assembly

32—
Voltage Regulator
33— Temperature Sending
Unit

34—
Oil
Pressure
Sending
Unit

35— Spark
Plugs
&
Cables

36—
Horn

37— Junction Block
38—
Marker
Lamp — Amber
through a
two-position
push-pull switch located on
the
left
side
of the control panel.
The
foot-operated
headlight dimmer switch is
mounted on the floorboard to the
left
of the steering
column.

H-9.
PRESTOLITE
DISTRIBUTOR
—
DAUNTLESS
V-6 and

HURRICANE
F4
ENGINE

The
Prestolite distributor on the F4
engine
is
mounted on the right
side
of the
engine
and is op­
erated by a coupling on the oil pump shaft, see Fig.
D-l,
which is driven by a spiral gear on the cam­
shaft. The spark advance is fully automatic, being controlled by built-in centrifugal
weights.
The Pres­

tolite
distributor on the V-6
engine
(Fig. H-8) is mounted at the
left
front of the
engine
on the tim­
ing chain cover. It is driven by a spiral gear on the
camshaft. The spark advance is fully automatic,
being controlled by built-in centrifugal
weights,
and by a vacuum advance system. While
some
parts of the distributor may be checked or replaced
with the unit mounted on the
engine,
it is
best
to periodically remove it for a thorough check. Infor­ mation covering the parts which can be serviced
without removal is
given
below.
The
Prestolite distributor installed on the V-6 en­

gine
is similar in construction to the distributor in­
stalled on the F4
engines
except
for the addition of

a
vacuum advance mechanism.
The
same checking procedures outlined in Par. C- 10a, are used for the Prestolite V-6 distributor with

exception
of specifications.
H-10. Distributor Cap

The
distributor cap should be inspected for cracks,
carbon runners and
evidence
of arcing. If any of

these
conditions
exists, the cap should be replaced.
Clean
any corroded high
tension
terminals.

H-11.
Rotor
Inspect the rotor for cracks or
evidence
of
excessive

burning at the end of the metal strip.
After a distributor rotor has had normal use the
end of the rotor will
become
burned. If burning is found on top of the rotor it indicates the rotor is
too short and
needs
replacing. Usually when this condition is found the distributor cap
segment
will 178

'Jeep'
UNIVERSAL
SERIES
SERVICE
MANUAL

H

12967
FIG.
H-6—WIRING
DIAGRAM—LATE
V6
ENGINE

1—Left Headlamp

2—
Left
Parking and Signal Lamp
3—
Right
Parking and Signal Lamp

4—
Right
Headlamp
5— Voltage Regulator
6—
Alternator
7—
Oil
Pressure
Sender

8— Temperature
Sender

9—
Ignition
Distributor
10— Junction Block

11—
Horn

12—
Ignition
Coil

13— Starting Motor
14— Battery Ground Cable 15— Foot Dimmer Switch 21-
16— Stop
Light
Switch — Front 22-
17— Ballast 23-
18—
Flasher
(Directional Signal) 24-
19—
Fuse
25-
20— Instrument Cluster 26-

A—Hi-Beam
Indicator 27-

B—Auxiliary
28- C—Instrument Lights 29-

D—Oil
Pressure
Indicator 30-
E—Charging Indicator 31-F—Temperature Indicator 32-
G—Fuel
Gauge
33-
H—Instrument Voltage Regulator 34-
-Ignition
and
Starter
Switch

-Horn
Button

-Directional
Signal Switch
-4-Way
Flasher
Switch

-Flasher
(4-Way)

-Fuse

-Main
Light
Switch
-Stop
Light
Switch —
Rear

-Fuel
Gauge
Tank
Unit

-Back-Up
Light
Switch

-Right
Tail
and Stop Lamp

-Right
Back-Up Lamp

-Left
Back-Up Lamp

-Left
Tail
and Stop Lamp
be burned on the horizontal
face
and the cap will

also
need
replacing. H-12. Condenser

The
condenser
prolongs
the
life
of the distributor

points
by
preventing
arcing at the
contacts.
It
also
provides
a
hotter
spark by creating a reverse
surge

of current which rapidly breaks
down
the
magnetic

field of the coil by
demagnetizing
the core. Should
the
condenser
be leaky, a weak spark will result.

Check
the
condenser
lead for broken wires or
frayed insulation. Clean and
tighten
the
connec-
179

H

ELECTRICAL
SYSTEM

ffKHs)

3—<§)

FIG.
H-7—WIRING
DIAGRAM—V6
ENGINE
CURRENT
MODEL
1—
Left
Headlamp
2—Left Parking and Signal Lamp
3— Right Parking and Signal Lamp
4—Right Headlamp 5—
Marker
Lamp — Amber
6— Alternator 7— Voltage Regulator
8— Starting Motor
9— Battery Ground Cable
10— 12 Volt Battery
11—
Flasher
(Directional Signal)
12— Instrument Cluster
A—Hi-Beam
Indicator
B—Auxiliary

C—Instrument
Lights

D—Oil
Pressure Indicator
E—Charging
Indicator

F—Temperature
Indicator

G—Fuel
Gauge Indicator
H—Instrument Voltage Regulator
13— Ignition and Starter Switch
14—
Horn
Button
15— Directional Signal Switch
16— 4-Way Flasher Switch 17—
Flasher
(4-Way)
18— Windshield Wiper Motor Switch
19—
Main
Light Switch
20—
Fuel
Gauge
Tank
Unit
21—
Back-Up
Light Switch
22—
Marker
Lamp — Red
23— Right
Tail
and
Stop
Light 24— Right Back-Up Lamp
25—
Left
Back-Up Lamp 26—
Left
Tail
and
Stop
Light
27—
Marker
Lamp — Red
28—
Stop
Light Switch
29— Foot Dimmer Switch
30— Windshield Wiper Motor Assembly
31—
Ballast
Resistor 32— Ignition
Coil

33—
Spark
Plugs and Cables 34— Temperature Sending Unit
35—
Oil
Pressure Sending Unit 36—
Horn
37— Junction Block
38—
Marker
Lamp — Amber

lions
on the terminal
posts.
Be sure
condenser
is
mounted
firmly on the distributor for a
good
ground
connection.

Should a
condenser
tester
be available the capacity for
both
F4 and Prestolite V6
condenser
should
check from .25 to .28 microfarads. In the
absence

of
tester,
check by substituting a new
condenser.

H-13. Distributor Points
a. Examine the distributor
points.
If
they
show

wear,
poor
mating, transferred metal, or pitting,

then
new
ones
should be installed. Clean the
points

with a suitable
solvent
and a stiff bristled brush.
b. Check the
alignment
of the
point
for a full,
square
contact.
If not correctly aligned, bend the
stationary
contact
bracket slightly to provide align­
ment.

c. The
contact
gap should be set at .020"
[0,508
mm.],
on the F4 and .016"
[0,406
mm.] on the
Prestolite V6. Adjustment of the gap is accom­ plished by
loosening
the lock screw and turning adjusting eccentric screw until correct gap is
secured. Be sure that the fiber block on the breaker

arm
is resting on the
highest
point
on the cam while the adjustment is
being
made. Recheck the gap
after locking the adjustment.
d. Apply a thin film of cam lubricant to the cam to
lessen
fiber block wear.
e. Using Tool C-4094, check
point
contact
spring
pressure, which should be
between
17 and 20

ounces
[0,487
a
0,567
kg.] on the F4 and 17 to 22 oz.
[0,487
a
0,624
kg.] on the Prestolite V6.

Check
with a spring scale
hooked
on the breaker

arm
at the
contact
and pull at right
angle
to the
breaker arm. Make the reading just as the
points

separate. Adjust the
point
pressure by
loosening
the stud holding the end of the
contact
arm spring
and slide the end of the spring in or out as
neces­

sary.
Retighten the stud and recheck the pressure. Too low a- pressure will
cause
engine
missing at
high
speeds.
Too high a pressure will
cause
rapid
wear of the cam, block, and
points.
180

'Jeep'
UNIVERSAL
SERIES SERVICE
MANUAL

H

12955

FIG.
H-8—PRESTOLITE
DISTRIBUTOR—DAUNTLESS V-6 ENGINE 1—
Cap
2—
Rotor

3—
Lubricating
Wick

4—
Snap
Ring
5—
Condenser

6—
Contact
Set 7—
Breaker
Plate
8—
Cam
and Stop Plate 9—
Spring
(2)
10—
Governor
Weight

11— Cam
Spacer

12—
Gear
13—
Gear
Pin
14—
Washer

15—
O-Ring
Seal
16—
Bushing

17—
Distributor
Housing 18—
Vacuum
Chamber
19—
Washer
(Nylon)
20—
—Cap
Clamp
and Rings

21—
—Primary
Lead
22—
Washer
(outer upper,

23—
Washer
(inner upper)

2".—Drive
Shaft
H-14. Governor Mechanism
The
centrifugal advance mechanism consists of

an
automatic cam actuated by two spring con­
trolled centrifugal weights. As the
speed
of the distributor shaft increases with
engine
speed, the

weights
are thrown outward against the pull of the springs.
This
advances the cam causing the contact
points
to
open
earlier and thus advancing the

spark.
The centrifugal
type
governor should be checked for free operation. Hold the governor shaft
and
turn the cam to the
left
as far as possible

and
release it. The cam should immediately return to the original position without drag. Should a distributor
test
fixture be available it is

best
to make a check through the entire advance
range, following the instructions of the fixture manufacturer.

The
vacuum control unit is mounted separately
on the
outside
of the distributor housing on the
V6
Prestolite distributor.
The
vacuum control unit consists of an enclosed
spring-loaded diaphragm linked mechanically to the distributor. The air-tight side of the diaphragm
is connected to the intake manifold side of the

carburetor.
Under part throttle operation, the in­take manifold vacuum is sufficient to actuate the
diaphragm and cause the distributor to rotate in
its mount, thus advancing the spark and increasing fuel
economy.
During acceleration or when the
engine
is pulling heavily, the vacuum is not suf­
ficient to actuate the diaphragm and the distributor
is held in the retarded position by a calibrated

return
spring which bears against the vacuum
diaphragm.

H-15.
Distributor Removal

a.
Remove high-tension wires from the distributor cap terminal towers, noting the order in which
they

are
assembled to ensure correct reassembly.
b. Remove the primary lead from the terminal

post
at the coil.
c. Unlatch the two distributor cap springs and re­
move
the cap.

d.
Note
the position of the rotor in relation to the
base.
This
should be remembered to facilitate re­ installing and timing.
e. Remove the screw holding the distributor to the

crankcase
and lift the assembly from the
engine.

H-16.
Prestolite Distributor Disassembly

Refer
to Fig. H-8 and H-9.

a.
Remove the rotor. b. Remove the condenser.
c. Remove the distributor points.
d.
Remove nylon washer attaching vacuum ad­vance arm to breaker plate, V6 only. Remove two 181

'Jeep'
UNIVERSAL
SERIES SERVICE
MANUAL

H

12746

FIG.
H-l8—VACUUM
ADVANCE
MECHANISM
(DELCO)

A—Full
Advance

B—No
Advance
1—Vacuum
Pull
Rod
e.
To adjust breaker point cam dwell and set tim­
ing of engine, refer to
Pars.
C-10 and
C-ll.
H-31. Coil
— V-6 Engine

The
sealed coil
does
not require any special service
other than keeping the terminals and wire connec­
tions clean and tight.

The
positive (+) terminal of the coil is connected
to the ignition switch through the ballast resistor,
and
is also connected directly to the starter
sole­

noid to by-pass the resistance during cranking of
engine.
The
negative (—) terminal is connected to the

distributor.
The secondary (high tension) terminal
is connected by a short cable to the center terminal
in
the distributor cap.

Always
make certain the coil wires are connected to the proper coil terminals to ensure correct
coil
polarity.

Note:
The ignition coil and ballast resistor must
be of the same manufacturer. Ballast resistors
and
ignition coils of one manufacturer are inter­changeable with both units of the other. H-32.
Ballast
Resistor

•
V-6 Engine.

An
ignition ballast resistor is in series with the
primary
winding of the coil. The ballast resistor
helps regulate the flow of
primary
current through­
out the speed range. At low
speeds
when the con­
tacts remain closed longer, the ballast heats and
increases in resistance, thereby limiting the flow of

primary
current. At higher
speeds
when the con­
tacts remain closed for shorter periods of time, the ballast
cools
and thereby decreases in resistance
to allow more
primary
current and reduce the
fall

off
in
available voltage.
During
starting, the resistor compensates for the lowered battery
voltage
re­
sulting from the starter load and permits an in­ crease in
primary
current, resulting in a higher
secondary
voltage
for starting.
The
only
test
required of the ignition ballast re­
sistor is a continuity check. Characteristics of the ballast produce wide variations in resistance with
changes in ballast temperature. Therefore, check­ ing
voltage
drop across the ballast would be mis­
leading.

Caution:
Never make a connection that connects
the ballast across the battery as this
will
burn
the ballast resistor winding.

H-33.
Spark
Plugs

Clean
and gap
spark
plugs as described in
Par.
C-4.
Inspect them for excessive burning and erosion of
electrodes, blistering of porcelain at the firing tip,

black
deposits, or fouling. These conditions indicate
that the plugs have not been operating at the cor­

rect
temperature.

Note:
Prolonged idling just before removing and
checking the plugs should be avoided as it may
produce false indications.

Spark
plug operating temperatures may have been
too hot, too cold, or normal as described.

a.
At too hot a temperature, the tip of the insulator
will
show
dark
spots
and blisters after fairly short service. As high-temperature operation is con­
tinued, the whole insulator
nose
will
discolor, show­
ing fused and blistered
deposits
near the electrode
as well as considerable erosion and burning of the
electrodes. After extreme service, the porcelain it­ self may be fused, cracked, and blistered at the tip.

The
electrodes
will
show extreme erosion and
burn­

ing and possibly even surface cracking.

Note:
If such cracking appears on certain plugs
after fairly short service, it may be caused by water
leaks in the associated cylinders.
b. At too cold a temperature plug operation, in
the early
stages,
will
result in a
dull
black
sooting

of the plug.
This
condition frequently is found in new vehicles during the break-in period and is no
indication of trouble in this case. As the condition progresses, black
deposits
of oil and carbon build
up on the base of the shell and on the insulator

until,
in extreme cases, the space
between
insulator

and
shell may be almost completely filled. Excessive
electrode erosion
will
seldom be found in cases of cold plug operation. These indications can be pro­
duced by the use of an excessively
rich
air-fuel mixture and the carburetor should be checked if
this condition is suspected. Fouling
will
also be
caused by leaking rings or intake valve
guides
that
permit excessive oil to reach the combustion
chambers.
The use of a hotter plug
will
help
burn

away
some
of this fouling but the mechanical con­ dition of the
engine
should be corrected.
c. In normal temperature operation the plug
will
accumulate grayish-tan to reddish-brown
deposits

with
fairly uniform discoloration of the insulator
nose
and slight, localized electrode erosion. If the
insulator shows any blotches, blisters,
irregular
dis­
coloration, etc., look for hot-plug symptoms. Too
hot or too cold plug operation may be caused by
the use of plugs of other than the specified heat

rating
but if the plugs are as specified a hotter or 187