ignition JEEP CJ 1953 Service Manual

B

LUBRICATION
B-2.
Special Lubricants

Special
lubricants are required for certain
lubri­
cation points on the 'Jeep' Universal vehicles. The

special
lubricants are necessary for proper function­ ing and maintenance of the vehicle. The
Lubrica­
tion
Chart
(Fig. B-l and B-2)
designates
the spe­
cial
lubricating points and identifies them by type

or
part number.

B-3.
Applying
Fresh
Lubricant

When
servicing or lubricating the vehicle, it is important that all old lubricant and
dirt
be re­ moved from the fitting and/or plugs before servic­
ing and that the recommended type of lubricant be used for the particular item being serviced.
Force
lubricant through the lube fittings until the lubricant being forced out of the joint is fresh

lubricant,
indicating that all old lubricant has
been removed.

B-4.
Engine
Lubrication
System —
Hurricane
F4 Engine

•
Refer to Fig. B-3.

The
engine
oil pressure system is designed to pro­
vide adequate lubrication to all working parts of
the engine. The gear-type oil pump is driven from
the
engine
camshaft. The pump is provided with a
FIG.
B-3—ENGINE
LUBRICATION
SYSTEM
—

HURRICANE
F4
ENGINE
floating, screened intake that prevents the
circula­

tion of any sediment that might accumulate in the

oil
pan. By means of this pump, the main bearing

journals
and crankpins are efficiently lubricated through an oil gallery and passages in the cylinder
block.
Oil
is forced under pressure to the main bear­
ings and through the cheeks of the crankshaft to
the connecting rod bearings. Oil is also force-fed
to the camshaft bearings, timing gears, and intake valve rocker arms. The oil pressure is controlled by

relief
valve located in the oil pump. The valve is
designed to open when excessive pressure
develops
in
the system, relieving the pressure and returning the
excess
oil to the oil pan. The cylinder walls,
piston pins, and tappets are supplied with oil from
spurt
holes
in the connecting rods. A portion of the oil is continually passed through an oil filter
which
effectively removes any foreign matter sus­ pended in the oil. A flanged section on the
rear
of
the crankshaft acts as an oil slinger and, in com­
bination with the
rear
main bearing upper and lower oil seal, prevents the leakage of oil from the

rear
end of the cylinder block. Leakage of oil from
the front end of the cylinder block is controlled by the crankshaft oil slinger and the front oil seal
installed in the timing gear cover. The oil pressure
indicator
light in the instrument panel and the oil level
gauge
or dip stick in the side of the
engine

provide a means for checking the oil pressure and

oil
level.

B-5.
Oil Pressure Gauge or Indicator
On
early
CJ-3B
vehicles an oil pressure
gauge
is
mounted on the instrument panel.
This
gauge
in­ dicates the oil pressure within the
engine
lubri­

cating system.

On
Models
CJ-5,
CJ-5A,
CJ-6,
CJ-6A,
DJ-5, DJ-6

and
later production vehicles of Model
CJ-3B
a
red
telltale lamp, which operates when the ignition
switch is turned on, is lit when there is insufficient
oil
pressure to properly lubricate the engine. When

it
goes
out, operating pressure is achieved. In
normal
operation, the light is lit when the ignition
is first turned on. It
goes
out after the vehicle is

in
motion.

Failure
of the
gauge
or indicator to register normal
oil
pressure may indicate insufficient supply of oil

in
the
engine
crankcase, low or no oil pump pres­
sure,
or a fault in the
gauge
or indicator electrical

circuit.
The
engine
must be stopped immediately to prevent possible damage to
engine
bearings and
the fault corrected before restarting the engine.

B-6.
Engine
Lubrication
System — Dauntless V-6 Engine

The
engine
lubrication system (Fig. B-4) is the
force
feed
type in which oil is supplied under pres­

sure
to the crankshaft, connecting rods, camshaft bearings and valve lifters. Oil is supplied under con­trolled volume to the rocker arm bearings and push

rods.
All other moving parts are lubricated by gravity flow or splash.

The
supply of oil is
carried
in the oil pan which is filled through a filter opening in the right rocker

arm
cover. A removable oil
gauge
rod on the left side of the crankcase is provided to check oil level.

The
oil pump is located in the timing chain cover 10

Jeep*
UNIVERSAL SERIES SERVICE
MANUAL

c
TUNE-UP

Contents

SUBJECT
PAR.

GENERAL
C-l

TUNE-UP
.C-2
Air
Cleaner
C-21

Battery
. C-3
Carburetor
Adjustments
C-2 5

Coil
C-20
Crankcase
Ventilation C-6

Cylinder
Compression C-9

Cylinder
Head(s) .C-5

Dash
Pot Adjustments .C-26

Distributor
Service C-10
thru
C-13

Distributor
Resistance Test C-l6

Fan
Belt
C-2 7
Fuel
Lines
and Screens
C-2
2

C-l.
GENERAL
An
engine tune-up should be performed for all
Jeep Vehicles each 6000 miles [9.600 km.] or at the end of each 250 hours off-the-road operation,
to ensure best possible performance at all times.
The
tune-up should follow the sequence given in
this section.
Because of federal laws limiting exhaust emissions,

it
is even more important that the engine tune-up is
done
accurately, using the specifications listed
on the tune-up sticker found in each engine com­

partment.

Note;
To ensure proper operation and effectiveness
of the exhaust emission control system, and to
comply with
Federal
and State requirements, a
recheck
of ignition timing, idle speed and idle mix­

ture
and necessary adjustments must be performed
after the first
2,000
miles [3.200 km.] of vehicle
operation.

A
minor engine tune-up should be performed every
6,000
miles [9.600 km.] or at the end of 250 hours
of off-the-road use.
Major
engine tune-up should
be performed every 12,000 miles [19.300 km.].

The
parts of units which affect power and perform­
ance may be divided into three groups:
(1) Units affecting compression
(2) Units affecting ignition
(3) Units affecting carburetion

The
tune-up procedure should cover
these
groups
in
the order given. While the items affecting com­
pression and ignition may be handled according
to personal preference, correction of items in the
carburetion
group should not be attempted until

all
items affecting compression and ignition have
been satisfactorily corrected.

Note:
To make sure hydro-carbon and carbon
monoxide emissions
will
be within limits, it is very

impotrant
that the adjustments be followed exactly
as listed on the sticker found in each engine compartment.
SUBJECT
PAR.

Fuel
Pump . . C-23

Heat
Control
Valve C-7

Ignition
Cables C-19

Ignition
Timing
. C-14

Ignition
Wires C-l8

Manifold
C-5

Manifold
Vacuum C-24

Point
Dwell C-17

Primary
Circuit
Tests
.................
C-15
Spark
Plugs C-4

Tappets
C-8

ROAD TEST C-2
8

SERVICE
DIAGNOSIS
. : C-29

TUNE-UP SPECIFICATIONS..
C-30

Minor
engine tune-up consists of the following.
Inspect
and correct as required:
Battery
cables and connections.
Alternator
and regulator wiring.

Primary
— Secondary wiring, distributor cap.

Cylinder
head torque.

Contact
point dwell.

Vacuum
and centrifugal advance.

Ignition
timing.
Spark
plugs for correct air gap.

Adjust
idle speed and idle air mixture.

Adjust
all drive belt tensions.
Clean
carburetor air cleaner.

Lubricate
exhaust manifold damper.

Major
engine tune-up includes the following.
Inspect
and correct as required:
Battery
condition and charging
circuit.
Clean,
lubricate
and tighten battery cable connec­
tions.

Ingition
system.
Spark
plugs; replace if necessary or clean and gap.

Compression
check.

Primary—Secondary
wiring, distributor cap.

Replace
contact points and condenser.

Lubricate
distributor cam with cam grease.
Adjust
contact points.

Check
vacuum and centrifugal advance. Set ignition timing.

Torque
cylinder head.
Adjust
idle speed and idle air mixture.

Replace
fuel filter element (every 12,000 miles [19.300
km.]).

Adjust
all drive belt tensions.

IMPORTANT: SPECIFICATIONS
FOR EN-

GINE
RPM.
DISTRIBUTOR POINT DWELL,
AND IGNITION TIMING GIVEN
IN
TUNE- UP SECTION
C
REFER
TO
VEHICLES
WITH
AND WITHOUT EXHAUST EMISSION CON­

TROL
SYSTEMS.

FOR
VEHICLES
EQUIPPED WITH EXHAUST
EMISSION CONTROL SYSTEMS ALSO
REFER
TO
SECTION
Fl (F4-134
ENGINE)
AND
F2 (V6-225
ENGINE).
19

c

TUNE-UP
C-2.
TUNE-UP SEQUENCE

The
following
Pars.
C-3 through
C-2
7
give the
sequence and describe the services to be performed
when tuning the engine.

C-3.
Clean
and
Check
Battery
Inspect
battery and cables. If the battery is not
satisfactory, install a fully-charged battery to allow
completion of the tune-up.
Note: If the battery fails any of the following tests,
remember that the cause may be other electrical
trouble, and not necessarily only a defective battery.
Refer
to Section H for electrical troubleshooting

and
tests.

a.
Check
the specific gravity of the eletrolyte in
each cell of the battery. A hydrometer reading of 1.260 indicates that the battery is fully charged.

If
the reading is 1.225 or below, the battery
needs

recharging.
If one or more cells is 25 "points" (.025)

or
more lower than the other cells, this indicates
that the cell is shorted, the cell is about to
fail,
or
there is a
crack
in the battery partition in the case.
Unless the battery is repaired or replaced, battery trouble
will
soon be experienced.

b.
Check
the electrolyte level in each cell, add

distilled
water to maintain the solution %" [9.5
mm.] above the plates. Avoid overfilling. Replace
the filler caps and tighten securely. It is important
to keep the electrolyte level above the plates at
all
times because plates that are exposed for any
length of time
will
be seriously damaged.

c.
Check
the wing nuts on the hold-down frame
for tightness. Tighten them only with finger pres­

sure,
never with pliers or a wrench. Excessive pres­

sure
could damage the battery case.

d.
Clean
the battery terminals and cable connec-
FIG.
C-l—FRAME
GROUND
STRAP
—

HURRICANE
F4
1—
Right
Front
Engine Mount

2—
Frame
Ground
Strap
DAUNTLESS
V-6
tors.
Prepare a strong solution of baking soda and

water
and brush it around the terminals to remove

any
corrosion that is present. The cell caps must
be tight and their vents sealed to prevent cleaning
solution entering the cells. After cleaning install
cable connectors on terminals and coat the ter­
minals
and connectors with heavy grease.
e. Inspect the battery cables and replace if badly

corroded
or frayed.
Check
tightness of terminal
screws to ensure
good
electrical connections.
Check

the tightness of the negative ground cable connec­ tion at the engine to ensure a
good
ground con­ nection.

f.
Load
test
the battery. Connect a voltmeter across the battery. Run the starting motor for 15 seconds.
If
the voltage
does
not drop below 10 volts on a 12 volt battery the battery is satisfactory. If the
voltage falls below
these
values, yet the specific
gravity
is above
1.225,
the condition of the battery
is questionable.

g.
Make sure the engine to frame ground strap or
cable connections are tight. If
these
connections
are
loose,
corroded or dirty,
hard
starting or failure
of the vehicle electrical system may result. Refer
to
Fig.
C-l
for location of the
Hurricane
F4 engine
to frame ground strap and its connections. Refer to Fig. C-2 for location of the Dauntless V-6 en­ gine to frame ground cable.

C-4.
Clean and
Adjust
Spark Plugs
Clean,
inspect, and gap
spark
plugs. Do not install

spark
plugs until completion of compression tests.

a.
Use a
Spark
Cable
and Installing
Plier
Tool,

W-2
74,
to remove the leads from the
spark
plugs.

Caution:
Pulling on the cables to remove them

from
the
spark
plugs can cause internal breaks in
the leads that
will
cause ignition failure.

b.
Using a
spark
plug wrench, loosen each
spark

plug one or two turns to break
loose
any carbon
deposits on the plug base. 20

c

TUNE-UP
C-13. Replacement and Adjustment of

Delco
Distributor Point Set

When
inspection of the contact points show re­ placement to be advisable, the following procedure
should be used. See Fig. C-13.

Note:
The service replacement contact point set
has the breaker spring tension and point alignment
adjusted at the factory.

Removal
of
Contact Point
Set

a.
Remove distributor cap by inserting a screw­

driver
in upper slotted end of cap retainers,
press

down and turn 90° counterclockwise. Push distri­
butor cap aside and remove rotor. Disconnect the condenser and primary leads from their terminal
by loosening the retaining screw. If there is no

retaining
screw, simply slip leads out.
b. Loosen two screws and lock
washers
which hold
the contact point set in place. Then remove point
set.

Installation
of
Contact Point
Set.

a.
Slide contact point set over
boss
on breaker
plate and under the two screw heads. Tighten two
screws and lock washers.

b.
Install
condenser and primary leads.

Note:
Leads must be properly positioned so they

will
not
come
in contact with
bottom
of weight
base or rotor.

c.
If
engine
does
not start readily, position contact

arm
rubbing block on peak of cam lobe, insert
V%"
[3,86 mm.] Allen wrench in adjusting screw and

turn
screw in (clockwise) until contact points

just
close. Then back screw out (counterclockwise)
V2
turn
(180°)
to obtain a point gap of approxi­
mately .016" [0,406 mm.] for a preliminary setting.

Adjustment
of
Contact Points
—
Engine Running
Note:
When adjusting contact point dwell angle,
always follow the instructions which
come
with the

dwell
meter.

a.
Connect dwell tester leads: red to distributor
side of coil, black to ground.

b. Turn
selector switch to position for
6-lobe
cam.

Turn
ignition switch on.

c.
Start engine.
Lift
adjustment window and insert
Vs"
[3,86 mm.] Allen wrench in adjusting screw.
Set dwell angle at 30 degrees. See Fig. C-14.

d.
After adjusting dwell angle, always check
ignition timing.

C-14.
Check
Ignition
Timing

a.
Hurricane F4 Engine.
If
a neon timing light is available, use it to check
igntion timing following the instructions of the
timing light manufacturer.

In
the absence of a timing light, remove No. 1

spark
plug and turn the
engine
over until No. 1
piston is on compression stroke as indicated by
air
being forced from No. 1 spark plug opening.
Turn
the
engine
slowly until the specified
degree
mark
on the timing gear cover is in alignment with
FIG.
C-l6—HURRICANE
F4
ENGINE

TIMING
MARKS
the notch on the crankshaft pulley. Fig. C-l6 shows
the timing pointer arrangement of the Hurricane
F4
engine. Refer to Ignition Timing Specifications
Par.
C-30. When the piston is positioned 5°
BTC,

timing is correctly set if the distributor rotor arm
points to No. 1 terminal in the distributor cap and
the distributor points are just ready to break. See
Fig.
C-12. Timing may be altered by loosening the

distributor
mounting clamp and turning the distri­
butor.
Turn
the distributor clockwise to advance
the timing and counterclockwise to retard the tim­
ing.
Do not overtighten the mounting clamp screw.
FIG.
C-l7—DISTRIBUTOR ROTATION
AND

FIRING
ORDER,
F4
ENGINE b.
Dauntless V-6 Engine.

Check
timing with a timing light connected to the

spark
plug of No. 1 cylinder (front cylinder, left

bank).
Yellow timing
mark
on the vibration damper must align with the specified
degree
mark

on the timing indicator (Fig.
C-18).
Refer to
Igni­

tion Timing Specifications Par. C-30. With the
engine
running at correct idle speed and the vacu­

um
advance
hose
disconnected from the distributor

and
the line plugged, check for correct timing
set­

ting. If necessary,
loosen
the distributor clamp bolt

and
rotate the distributor until proper alignment of timing marks is attained. Tighten mounting

screw.
After correct setting is made, unplug the

vacuum
line and reconnect it, operate the
engine
and
check operation of the vacuum advance.

Note:
Turn
the distributor counterclockwise to ad­
vance timing; turn clockwise to retard timing. 28

'Jeep'
UNIVERSAL
SERIES
SERVICE
MANUAL

C

FIG.
C-18—DAUNTLESS
V-6
ENGINE
TIMING
MARKS
C-15.
Primary
Circuit
Tests

Excessive
voltage
drop in the primary circuit
will

reduce the secondary output of the ignition coil,
resulting in hard starting and poor performance. Inspect all primary wiring for
loose
or corroded
terminals, worn insulation, and broken strands,
a.
Connect voltmeter positive (-J-) lead to the
positive battery terminal, as shown in Fig. C-20.
The
negative
lead (—) is connected to the ignition
side of the resistor on Dauntless V-6
engine.
The

negative
lead (—) is connected to the ignition
pri­

mary
of the coil on Hurricane F4
engine.
Con­
nect a jumper wire from the distributor primary

terminal
of the coil to the ground. Be sure all lights and accessories are off. b. With the ignition switch on, the
voltage
should
not
exceed
.4 volts. More than .4
volts
indicates

excessive
resistance
exists
in the battery cable, ignition switch wiring, or the ignition switch. The

excessive
resistance may be located with voltmeter checks across each section of the circuit.
c. Remove the jumper wire from the coil. Connect
the voltmeter positive (-f) lead to the distributor
terminal
of the ignition coil. Ground the
negative
(—) lead of the voltmeter.
12156
FIG.
C-20—IGNITION
PRIMARY
CIRCUIT

RESISTANCE
CHECK

1—
Distributor

2—
Distributor
Primary
Terminal

3—
Coil

4— Ignition Resistor 5— Ignition Switch 6— Ignition Switch Side of Resistor 7— Positive Battery
Terminal

8—
Battery

9—
Jumper
Wire
d.
Note
the
voltage
with the ignition switch on.

If
battery
voltage
is indicated, the distributor

breaker
points
are open. Rock the
engine
to
close

the points. Voltage
less
than .2 volt indicates the

points
are satisfactory. Voltage more than .2 volt indicates burned or high resistance in the ignition

points
or a poor distributor ground.

C-l
6. Distributor
Resistance
Test

A
dwell tester is used for the following
tests.
Ex­
cessive resistance in the ignition primary circuit,
from the distributor side of the coil through the

points
and to the distributor ground,
will
prevent
the coil from producing sufficient output for
good
overall
ignition. Any resistance in this portion of
the ignition system
will
be indicated on the dwell
FIG.
C-21—DISTRIBUTOR
RESISTANCE
CHECK

14242

FIG.
C-19—DISTRIBUTOR
ROTATION
AND
FIRING
ORDER,
V-6
ENGINE

29

c

TUNE-UP
meter during this
test
Connect the red lead
tc*
dis­

tributor
primary
lead at the coil as shown in Fig.
C-21.
Connect black lead to the ground.
Turn

ignition switch on; with
engine
stopped, observe
dwell
meter. If the meter reads zero,
crank
the

engine
a fraction of a revolution to
close
the

breaker
points.

Distributor
resistance is normal, if dwell meter
pointer is within range of
black
bar. Distributor resistance is high, if
dwell
meter pointer is not

within
the black bar.
Remove test lead from
distri­
butor terminal of coil and
connect
to
each
of the
following points to determine
where
the excessive resistance is:

Distributor
primary
terminal

Distributor
primary
terminal in the distributor

Breaker
point bracket
Ground
side of points

Distributor
housing

Where
a noticeable change occurs in the meter
reading
in
these
steps, make the necessary correc­
tion and repeat the
test.

C-l 7. Distributor
Point
Dwell

Using
a dwell tester, connect red
lead
to the
distri­

butor terminal at coil. Connect black lead to
ground.
Set selector switch to the number of
cylin­

ders in the
engine
being tested. Operate
engine
speed at specified rpm. and
note
readings. Cam

dwell
angle must be 30° for the Dauntless V-6
Delco equipped engine, 29° ±: 3° Prestolite equipped
engine
and 42° for the
Hurricane
F4 engine. If the dwell reading is not to specifications,
trouble could be improper point spacing, point

rubbing,
defective block or breaker arm, or mis­
aligned and worn distributor cam.
Adjust
dwell
as shown in Fig. C-14 for the Delco equipped
Dauntless V-6 engine. For cam dwell adjustment
of the Prestolite equipped V6 and
Hurricane
F4 engine, refer to Par. C-10,
step
a.

Dwell
variation is determined by noting any
dwell
change as the
engine
is operated at different
speeds.

Excessive
variation indicates a change in point opening that can result from shaft or bushing wear,

or
from the distributor plate shifting because of

wear
or
looseness.

Measure
dwell variation at idle speed, using same

test
hookup for checking dwell. Increase speed to 1750 rpm.;
note
dwell reading.
Then
slowly reduce
speed to idle while observing dwell meter. Dwell

variation
should not exceed 3°. If dwell variation
exceeds
3°
between
idle speed and 1750 rpm.,
probable wear in the distributor shaft, bushings, or

breaker
plate is indicated. Distributor should then be checked more thoroughly.

C-l8. Check Ignition Wires
and
Connections

Examine
and clean the insulation on all ignition

wires
and check all connections. Wires should be
firm,
flexible, and free from roughness and minute
cracks.
Bend wires to check for brittle,
cracked,
or

loose
insulation. Since defective insulation
will
per­

mit
crossfiring or missing of the engine, defective

wires
should be replaced.

C-l9. Test Ignition
Cables

To
remove cables from
spark
plugs, use
Spark
Plug
Cable
Remover
Tool
W-274.
Twist
the
boot

slightly to break the seal and, grasping the rubber
protector
boot,
lift straight up with a steady even

pull.
Do not grasp the cable and
jerk
the cable off; this
will
damage the cables. Do not use a probe
on
these
wires; puncturing them may cause a
separation in the conductor. To remove ignition cables from the distributor cap or coil tower,
loosen

the nipple first, then grasp the upper part of the nipple and the cable and gently
pull
straight up.

Test
the cable with an ohmmeter. Resistance value

per
foot
is
3000-7000
ohms. The ignition cables
can
be checked for
circuit
continuity by removing
the cable from the
spark
plug and holding the cable
end Vi" [6,35 mm.] from the engine. A strong

spark
indicates
good
conductor continuity.

When
connecting the cable to the
spark
plug, be
certain
a
good
connection is made and that the
protector
boot
fits tight on the
spark
plug. A
partially
seated cable creates an additional gap in
the
circuit
and the resulting
spark
jump
will
cause

terminal
corrosion and cable damage.

C-20. Coil

When
an ignition coil is suspected of being defec­ tive, it should be checked on the car. A coil may

break
down after it has reached operating tempera­
ture.
It is important that the coil be at operating
temperature when
tests
are made.

Note:
The ignition coil and ballast resistor for the

V-6
engine
must be of the same manufacturer.
Ballast
resistors and ignition coils of one manufac­

turer
are interchangeable with both units of the
other.
C-21.
Service Air
Cleaner

Refer
to Par.
B-2 2
for the correct service of the

air
cleaner.

C-22.
Check Fuel Lines and
Screens

Check
all fuel line connections to guard against
leakage.
Check
fuel pump filter F4
engine
and
fuel
line filter V-6 engine. Replace fuel filter if
necessary.

C-23. Check Fuel Pump a.
Fuel
pump pressure is important, for low pres­

sure
will
seriously affect
engine
operation and high

pressure
will
cause excessive fuel consumption and
possibly flood the carburetor. Should there be any doubt of normal operation, check the pressure with
a
gauge
as shown in Fig.
C-2 2.
The minimum and

maximum
allowable pressures are 2% to 3% lbs. [0,176 a
0,264
kg-cm2], for the
Hurricane
F4 en­
gine.
Fuel
pump pressure at carburetor (inlet) on
the Dauntless V6-225
engine
should be 3% lbs.
[0,264
kg-cm2] minimum at specified
R.P.M.
idle

with
the vapor
return
hose
squeezed off.
With
the

vapor
return
hose
open pump pressure should be
2
V2
lbs. [0,176 kg-cm2] minimum.

b.
Test for volume, as a pump may build up suffi­
cient pressure but
fail
to produce sufficient volume.
Turn
down the carburetor fuel line fitting on the
pump and with the tank line connected, pump out
30

'Jeep'
UNIVERSAL
SERIES
SERVICE
MANUAL

C

FIG.
C-22—-CHECKING
FUEL
PUMP
PRESSURE
—
DAUNTLESS
V-6
ENGINE a
couple of strokes to be sure the pump is primed.

Using
a half-pint
bottle
or similar measure, pump
Vi
pint [0,24 It] of fuel by cranking the
engine

with
the starter motor. Count the strokes neces­
sary
to
fill
the measure. If more than 20 strokes

are
required, the fuel pump is inefficient, the tank
line is leaking air, or the fuel supply is restricted.

Check
fuel filter in the fuel tank if line is restricted.

C-24.
Check Manifold Vacuum

To
check the intake manifold vacuum on the
Hurri­

cane F4 engine, remove the ventilation valve and

L
fitting from the manifold and install special adapter. On the Dauntless V-6
engine
remove the
pipe plug located in the right
rear
of the intake
FIG.
C-23—CHECKING MANIFOLD VACUUM
—

HURRICANE
F4
ENGINE
manifold and install special adapter. Connect the

vacuum
gauge
tube to the special adapter as shown

in
Fig. C-23 for the
Hurricane
F4 engine.

Start
the engine. Connect a Tachometer
Tool,

C-3896,
from the distributor
primary
terminal to ground and set the
engine
speed at the specified

rpm.
given in Par. C-30. Observe the vacuum
read­

ing and interpret as follows:

a.
A steady reading from 18" to 20" [457 a 508
mm.] of mercury is a normal reading, indicating
that valve and
spark
timing, valve seating, and
piston ring sealing are all satisfactory.
b. A steady but below normal reading indicates

a
condition common to all cylinders such as a

leak
at the carburetor gasket, late ignition or valve
timing, or uniform piston ring and bore wear.

c.
A slowly fluctuating or drifting reading in­ dicates that the carburetor idle mixture is incorrect

Look
for the cause in the fuel system.

d.
A rhythmic pulsating reading is caused by a
condition affecting one or more cylinders, but not

all,
and indicates leaky valve, gasket blowby, re­
stricted intake port, or an electrical miss.
e. An intermittent pulsating reading is caused by

an
occasional malfunction, such as a sticking valve
(all
valves may be
erratic
in operation if the valve
springs are weak), electrical miss caused by insuffi­
cient distributor point tension or low coil
voltage

coupled with inconsistent
spark
plug
gaps
or fouled
plugs, or
dirt
in the fuel system finding its way into
passages of
critical
size or valve
seats
in the
car­

buretor.

f.
A normal reading that quickly falls off (with

engine
running at
2000
rpm.) indicates exhaust
back
pressure caused by a restriction in the exhaust
system.

g.
Make indicated corrections to bring vacuum to 18" to 20" [457 a 508 mm.] of mercury normal

reading.

C-25.
Carburetor Adjustments

•
Refer to Fig. C-24, C-25 and C-26.

Carburetor
adjustments should not be attempted

until
it is known that
engine
ignition and com­
pression are in
good
order. Any attempt to adjust

or
alter the carburetor to compensate for faulty conditions elsewhere
will
result in reduced econ­
omy and overall performance.

Caution:
If an
engine
is idling too slow or rough,
this may be caused by a
clogged
ventilator valve

or
hose;
therefore, never adjust the carburetor idle
without first checking the crankcase ventilator
check valve and
hose.

The
air cleaner must be left in place while making
idle speed and mixture adjustments. All lights and accessories, must be turned off. The positive
crank­

case ventilator system should also be in
good
oper­
ating condition when making carburetor adjust­ ments.
Either
of
these
items noticeably affects the

air
fuel ratio at idle.

•
Hurricane
F4 Engine.
Note:
The idle mixture adjustment procedure for
the late model
YF-4941S
and
YF-6115S
Carter

31

c

TUNE-UP
Carburetor
equipped with the
External
Idle Mix­
ture
Limiter
Cap is the same as outlined below
in
Pars.
"A"
through
"D";
however, because of the
Idle
Limiter
Cap,
the idle mixture screw
CANNOT

be adjusted in the counter-clockwise
(rich)
direc­
tion. The adjustment is made from the
rich
stop
position and the mixture screw is turned in (clock­
wise) approximately 3A turn to
"Lean
Best Idle."

Refer
to Fig. C-25.

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 or vacuum
gauge
to engine.

c.
Warm
up
engine
and stabilize temperatures.
d.
Adjust
engine
idle to speed desired, using throt­
tle idle speed adjusting screw.

e.
Carburetors without Idle
Limiter
Cap turn idle
mixture screws out (counterclockwise) until a
loss
of
engine
speed is indicated; then, slowly turn mix­
ture screw in (clockwise-leaner) until maximum speed (RPM) is reached. Continue turning in (clockwise) until speed
begins
to drop; turn mix­
ture adjustment back out (counterclockwise-richer)

until
maximum speed is just regained at a "lean as possible" mixture adjustment. Refer to
Fig.
C-24.
FIG.
C-24—CARBURETOR —
HURRICANE F4 ENGINE,
EARLY
MODEL 1—
Choke
Clamp Bracket
2—
Choke
Shaft and
Lever
Assembly

3—
Fuel
Inlet Elbow
4—
Bowl
Vent Tube 5— idle Air Adjusting
Needle
6—
Throttle
Lever
and Shalt Assembly
7—
Idle
Speed Adjusting Screw
8—
Fast
Idle Connector Rod
FIG.
C-25—CARBURETOR —
F4 ENGINE,
LATE
MODEL 1—
Choke
Clamp Bracket
2—
Throttle
Lever
and Shaft

3—
Choke
Shaft and
Lever

4 Bowl Vent Tube 5—
Fuel
Inlet Elbow 6—
Dash
Pot Bracket 7—
Throttle
Lever
8—
Dash
Pot Plunger
9—
Dash
Pot Assembly
10—
Lock
Nut
11— Stop Pin
12—
Idle
Mixture
Limiter
Cap 13—
Idle
Speed Adjusting Screw
14—
Fast
Idle Connecting Rod
Note:
When adjusting the mixture screw never
seat the screw tight during the adjustment proce­

dure
as this can damage the screw needle.

•
Dauntless V-6 Engine.

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 stablize temperatures.
d.
Adjust
engine
idle to speed desired, using throt­
tle idle speed adjusting screw.
Note:
The
Carter
YF-6115S
Carburetor
has a throt­
tle return spring attached from the carburetor

main
body to the carburetor throttle shaft The purpose of this spring is to return the throttle
to idle speed position should a linkage failure
occur.
FIG.
C-26—CARBURETOR —
DAUNTLESS V-6 ENGINE 1—
Fuel
Inlet
2—
-Choke
Housing

3—
Choke
Cable Bracket
4—
Idle
Speed Adjusting Screw
5—
Idle
Fuel-Air
Mixture Screws 32

'Jeep*
UNIVERSAL
SERIES
SERVICE
MANUAL

C

FIG.
C-2
7—FAN
BELT
—
DAUNTLESS
V-6
ENGINE
e. Adjust mixture by turning idle mixture screws
out (counterclockwise) until a loss of engine speed
is indicated; then, slowly
turn
both mixture screws

in
clockwise (leaner) until maximum speed (RPM)
is reached. Continue turning in (clockwise) until a slight drop in speed (RPM) is noted. Make certain
both mixture screws are adjusted equally.
This
will

ensure a "lean as possible" mixture adjustment.

Readjust
idle
stop
screw to idle engine at the
specified
R.P.M.

Note:
This
method of adjusting idle mixture must
be used to keep hydrocarbon and carbon monoxide
emissions to a minimum.

Note:
No fast idle speed adjustment is required.

Fast
idle is controlled by the curb idle speed ad­ justment screw. If the curb idle speed is correctly set, the fast idle speed
will
be correct.
C-26.
Dash
Pot
Adjustment

Refer
to Section
E, Par.
E-44 for proper carburetor

dash
pot adjustment procedure.

C-27.
Check
Fan
Belt

The
fan belt drives the fan, alternator, and water

pump.
See Fig. C-27.

Inspect
the fan belt for serviceability and proper
tension. The tension should be checked with the
Belt
Tension Gauge, W-283. The correct tension on a used belt is 70 to 80 pounds [31,7 a 36,2 kg.]

and
on a new belt 110 to 120 pounds [49,8 a 54,5 kg.]. When preparing for delivery of new car,
the belt strand tension should be 80 to 110 pounds [36,2 a 49,8 kg.]. When installing a new belt, adjust
the strand tension 110 to 120 pounds [49,8 a 54,5 kg.].

Adjust
the fan belt tension by loosening the clamp
bolt on the alternator brace and swinging the alter­

nator
away from the engine until proper belt ten­
sion is obtained.
Then
tighten the clamp bolt.

Note:
If no
gauge
is available approximate correct
tension is obtained when the thumb pressure mid­
way between the pulleys causes the belt to flex
y%
inch
[IV4
cm.].

C-28.
ROAD TEST VEHICLE

After
completing the tune-up, road
test
the vehicle for power and overall performance. Make neces­
sary
adjustments.

Note:
Engine run on or "dieseling" is a condition

in
which combustion continues to take place after
the normal ignition
spark
from the distributor has
been shut off by turning off the ignition switch. It is generally caused by excessive engine idle speed

in
combination with retarded ignition timing, en­ gine heat soak or the use of low octane fuel.

Should
engine dieseling (engine running after igni­
tion key is turned off) be experienced on V-6 engine equipped vehicles, installation of Idle Stop
Valve
Kit
Part
No. 991722
will
correct the

difficulty.
33

TUNE-UP

C-29.
SERVICE
DIAGNOSIS

POOR
FUEL ECONOMY Ignition Timing Slow or Spark Advance Stuck

Carburetor
Float High
Accelerator Pump Not Properly Adjusted High Fuel Pump Pressure

Fuel
Leakage

Leaky
Fuel Pump Diaphragm Loose Engine Mounting Causing High Fuel Level in Carburetor

Low
Compression
Valves Sticking
Spark
Plugs Bad

Spark
Plug Cables Bad
Weak
Coil
or Condenser Improper Valve Tappet Clearance

Carburetor
Air Cleaner Dirty
High Oil Level in Air Cleaner Dragging Brakes

Front
Wheels Out of Alignment

Tires
Improperly Inflated Inaccurate Odometer

Faulty
Fuel Tank Cap
Clogged
Muffler or Bent Exhaust Pipe Sticking Exhaust Manifold Valve

LACK
OF POWER
Low
Compression Ignition System (Timing Late)
Improper Functioning Carburetor
or Fuel Pump

Fuel
Lines
Clogged

Air
Cleaner Restricted Engine Temperature High Improper Tappet Clearance
Sticking Valves
Valve Timing Late

Leaky
Gaskets
Muffler
Clogged

Bent Exhaust Pipe Sticking Exhaust Manifold Valve —
Dauntless V-6 Engine

LOW
COMPRESSION
Leaky
Valves Poor Piston Ring Seal Sticking Valves
Valve Spring Weak or Broken
Cylinder
Scored or Worn
Tappet Clearance Incorrect Piston Clearance too Large

Leaky
Cylinder Head Gasket

BURNED
VALVES AND SEATS Sticking Valves or too Loose in Guides
Improper Timing
Excessive Carbon Around Valve Head and Seat Overheating
Valve Spring Weak or Broken
Valve Tappet Sticking
Valve Tappet Clearance Incorrect
Clogged
Exhaust System

Defective
Valve
Lifter
— Hydraulic
VALVES
STICKING
Warped Valve Improper Tappet Clearance Carbonized or Scored Valve
Stems

Insufficient Clearance Valve Stem to Guide
Weak or Broken Valve Spring Valve Spring Cocked Contaminated Oil

OVERHEATING
Inoperative Cooling System
Theromstat Inoperative Improper Ignition Timing
Improper Valve Timing
Excessive Carbon Accumulation
Fan
Belt too Loose

Clogged
Muffler or Bent Exhaust Pipe
Oil
System Failure Scored or Leaky Piston Rings
Sticking Exhaust Manifold Valve — Dauntless V-6 Engine

POPPING-SPITTING-DETONATION
Improper Ignition Improper Carburetion
Excessive Carbon
Deposit
in
Combustion Chambers
Poor Valve Seating Sticking Valves
Broken Valve Spring Tappets Adjusted too Close
Spark
Plug Electrodes Burned
Water or Dirt in Fuel
Clogged
Lines Improper Valve Timing

Clogged
Fuel Filter Sticking Exhaust Manifold Valve —
Dauntless V-6 Engine

EXCESSIVE
OIL CONSUMPTION Piston Rings Stuck in Grooves, Worn or Broken Piston Rings Improperly Fitted or Weak Piston Ring Oil Return
Holes
Clogged

Excessive Clearance, Main and
Connecting Rod Bearings

Oil
Leaks at Gaskets or Oil Seals
Excessive Clearance, Valve Stem
to Valve Guide (Intake)

Cylinder
Bores Scored, Out-of-
Round or Tapered
Too Much Clearance, Piston to Cylinder Bore
Misaligned Connecting Rods
High Road
Speeds
or Temperature
Crankcase
Ventilator Not Operating

BEARING
FAILURE
Crankshaft
Bearing Journal Out-of-Round

Crankshaft
Bearing Journal Rough

Lack
of Oil
Oil
Leakage

Dirty
Oil

Low
Oil Pressure or Oil Pump Failure

Drilled
Passages
in Crankcase or Crankshaft
Clogged

Oil
Screen Dirty
Connecting Rod Bent 34