1953 JEEP DJ Service Manual

'Jeep*
UNIVERSAL SERIES SERVICE
MANUAL

COMPRESSION PRESSURE LIMIT CHART

Maximum
Pressure
Minimum

Pressure
Maximum

Pressure
Minimum

Pressure

psi.
kg-cm2
psi.
kg-cm2
psi.

kg-cm2

psi.

kg-cm2

134 9,42 101 7,10
188
13,22 141
9,91
136 9,56 102 7,17 190
13,36 142
9,98
138 9,70 104 7,31 192
13,50 144 10,12
140 9,84 105 7,38 194
13,64 145
10,19
142 9,98 107 7,52 196
13,78 147 10,33
144 10,12 108 7,59 198
13,92
148 10,40
146 10,26 110 7,73 200
14,06 150 10,55
148 10,40 111 7,80
202
14,20 151
10,62
150 10,55 113 7,94 204
14,34 153
10,76
152 10,68 114 8,01 206
14,48 154 10,83
154 10,83
115 8,08 208
14,62 156
10,97
156 10,97 117 8,23
210
14,76 157 11,04
158 11,11 118 8,30 212
14,90
158 11,11
160 11,25 120
8,44 214
15,04 160
11,25
162 11,39 121 8,51 216
15,18 162 11,39
164 11,53
123 8,65 218
15,32 163
11,46
166 11,67 124 8,72 220
15,46 165 11,60
168 11,81 126 8,86 222
15,61 166
11,67
170 11,95 127 9,83 224
15,75 168 11,81
172 12,09 129 9,07 226
15,89 169
11,88
174 12,23 131 9,21 228
16,03 171 12,02
176 12,37 132 9,28 230
16,17 172
12,09
178 12,51 133 9,35 232
16,31
174 12,23
180 12,65 135 9,49
234
16,45 175 12,30
182 12,79 136 9,56 236
16,59 177 12,44
184 12,94 138 9,70
238
16,73 178 12,51
186 13,08 140 9,84
b.
Dauntless V-6 Engine.

To
check the
engine
cylinder compression use the
following procedures:

Firmly
insert compression
gauge
in
spark
plug
port
(Fig.
C-10).
Crank
engine
through at least four
compression strokes to obtain highest possible

reading.

Check
compression of each cylinder. Repeat com­
pression check and record highest reading obtained on each cylinder during the two pressure checks.

Note:
The recorded compression pressures are to
be considered normal if the lowest reading cylinder
is more than seventy-five percent of the highest

reading
cylinder. See the following example and
the "Compression Pressure
Limit
Chart".
Example:

Cylinder
No. 1 2 3 4 5 6

Pressure
(psi.) 129 135 140 121 120 100
Seventy-five percent of 140 (highest) is 105.
Thus,

Cylinder
No. 6 is
less
than seventy-five percent
of
Cylinder
No. 3.
This
condition, accompanied by low speed missing, indicates an improperly seated
valve or worn or broken piston
ring.

If
one or more cylinders read low, inject about

a
tablespoon of
engine
oil on top of pistons in low

reading
cylinders through
spark
plug port. Repeat compression check on
these
cylinders.

If
compression improves considerably, rings are

worn.
If compression
does
not improve, valves are

sticking
or seating poorly.

If
two adjacent cylinders indicate low compression

and
injecting oil
does
not increase compression, the
cause may be a head gasket leak
between
the

cylinders.
Engine coolant and/or oil in cylinders could result from this
defect.
FIG.
C-10—CHECKING ENGINE CYLINDER
COMPRESSION
—
DAUNTLESS
V-6
ENGINE
FIG.
C-l
1—CONTACT
POINTS
MATERIAL
TRANSFER

25

c

TUNE-UP
C-10.
Distributor
Service

The
distributor cap should be inspected for
cracks,

carbon runners and evidence of arcing. If any
of
these
conditions exists, the cap should be re­
placed.
Clean
any corroded high tension terminals. Inspect the rotor for cracks or evidence of
exces­

sive 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 con­
dition is found the distributor cap
segment
will

be burned on the horizontal face and the cap
will

also need replacing.
Check
the condenser lead for broken wires or

frayed
insulation.
Clean
and tighten the connec­
tions
on the terminal
posts.
Be sure the condenser
is mounted firmly on the distributor for a
good
ground connection. Should a condenser tester be available the capacity
should be checked. In the absence of a tester check
by substituting a new condenser.
Examine
the distributor
points
(Fig.
C-ll).
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.
Check
the alignment of the point for a
full,
square
contact. If not correctly aligned, bend the station­
ary
contact bracket slightly to provide alignment,

a.
Hurricane F4 Engine (Prestolite).

The
contact gap of the distributor point on the

Hurricane
F4
engine
should be set at .020"
[0,508

mm.],
measured with a wire
gauge.
Adjustment of
the gap is accomplished by
loosening
the lock screw and turning adjusting eccentric screw (Fig.
C-12)
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.

Apply
a thin film of cam lubricant to the cam to
lessen fiber block wear. Should a condenser tester be available the capacity
should check from .21 to .25 microfarads. In the
absence of a tester check by substituting a new
condenser.

Check
point contact spring pressure, which should
be
between
17 and 20
ounces
[0,487
a 0,56 kg.].
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.
b. Dauntless V-6 Engine (Delco).

The
spark advance is fully automatic being con­
trolled by built-in centrifugal weights, and by a vacuum advance system (Fig.
C-13).
The same
checking procedures are used as (a)
above
except,

the capacity of the condenser must be .18 to .23 microfarads and the contact gap should be set at
.016"
[0,406
mm.]. Adjustment of the gap is made
by rotating the socket head adjustment screw with
a
Vs" [3,86 mm.] Allen wrench (Fig.
C-14).

The
contact spring pressure must be 19 to 23 ozs.
[0,538
a
0,652
gr.] and the cam dwell
angle
is

30°,
with distributor vacuum line disconnected.
The
preferred method of adjusting cam dwell re­
quires turning of the adjusting screw until the specific dwell
angle
is obtained as measured by a
dwell
angle
meter. Refer to Par. C-l7. To adjust
the cam dwell by an alternate method, turn the adjusting screw in (clockwise) until the
engine

FIG.
C-12—PRESTOLITE DISTRIBUTOR HURRICANE F4 ENGINE
1— Condenser
2—
Lubricating
Wick

3—
Breaker
Cam
4—
Breaker
Arm Pivot 5—
Distributor
Cap (Rotation &
Firing
Order)
6—
Distributor
Points 7— Adjustment
Lock
Screw
8—
Adjusting
Eccentric
Screw
9—
Oiler

10—Primary
Wire
26

'Jeep*
UNIVERSAL
SERIES SERVICE
MANUAL

C
12763

FIG
C-13—
DELCO
DISTRIBUTOR —
DAUNTLESS V-6 ENGINE
1—
Rotor
8—Access Passage

2—
Breaker
Plate Assembly 9—Shaft Bushing
3—
Lubrication
Reservoir 10—Vacuum Assembly
4—
Primary
Terminal
11—Cam
5—
Distributor
Housing 12—Weight Assembly 6—
Shaft
Bushing 13—Cap
7—
Gear
begins
to misfire, then
give
the wrench one-half

turn
in the
opposite
direction (counterclockwise),
thus giving the approximate cam dwell angle re­
quirement

Note:
Prestolite and Delco distributors are inter­
changeable on V-6
engine
equipped vehicles.

c.
Dauntless V-6 Engine (Prestolite).
•
Refer to Fig. C-l5.

The
Prestolite distributor installed on the V-6
engine
is similar in construction to the distributor
installed on the F4
engine
except for the addition
of a vacuum advance mechanism.

The
spark advance is fully automatic being con-
FIG.
C-14—ADJUSTING CONTACT POINT GAP —
DAUNTLESS V-6 ENGINE (DELCO) trolled by built-in centrifugal weights, and by a

vacuum
advance system.

The
same service checking procedure outlined
in
Par.
C-lOa,
are used for the Prestolite V-6

distributor
with exception of specifications. 12963

FIG.
C-15—-PRESTOLITE DISTRIBUTOR V-6 ENGINE
1—
Vacuum
Advance Unit
5—Lubricating
Wick

2—
Distributor
Points 6—Condenser

3—
Breaker
Arm Pivot 7—Adjusting
Eccentric
Screw
4—
Distributor
Cap 8—Adjusting
Lock
Screw
(Rotation
&
Firing
Order)
Specifications for the V-6 Prestolite distributor are
as follows. The condenser capacity must be .25 to 28 mfd., contact breaker arm tension 17 to 22
ounces [482 a 624 gr.], and breaker point gap .016" [0,406 mm.]. The cam angle must be set
at 29° ±3° with distributor vacuum line discon­
nected.

C-11.
Replacement and Adjustment of Prestolite

Distributor Point
Set — V-6
Engine

Replace
the Prestolite distributor contact set as
follows:
a.
Remove the distributor cap from the distributor.
Remove the rotor.
b. The condenser and primary leads are retained
by breaker point spring tension. Refer to Fig.

C-12
and C-15. Relieve spring tension to remove
the leads.
c. Remove the contact set retaining screw and remove the contact set.

d.
Remove the condenser screw and remove the condenser.
e.
Install
new parts by reversing the removal pro­
cedure. Relieve spring tension of the breaker point

spring
to install the primary and condenser leads.

f.
Rotate the crankshaft until the distributor cam
holds the distributor points to a wide-open position.

Check
the gap
between
the points. Then slightly

loosen
the contact set mounting screw and adjust
the contact point gap to the proper dimension.

Tighten
the mounting screw when correct gap is attained.
C-12. Breaker
Lever
Spring Tension
One
of the most important items to check is the

breaker
lever spring tension.
This
is checked with

a
spring scale hooked immediately behind the

breaker
lever contact. Spring tension required to
open the contact points are given in Par. C-10. 27

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