JEEP CJ 1953 Service Manual

'Jeep'
UNIVERSAL
SERIES
SERVICE
MANUAL

F F-8.
Exhaust
Pipe Replacement

When
replacing the exhaust pipe(s) refer to
Figs.
Fl,
F2 and
F-3.
Remove the nuts securing the ex­
haust pipe(s) to the exhaust manifold(s), loosen

and
disconnect mounting
clamp
(s)
as necessary, loosen clamp securing exhaust pipe to muffler and
remove exhaust pipe(s).
Note: Always use new gasket(s) between exhaust
pipe(s) and exhaust manifold(s). After installation
of exhaust pipe(s), check the exhaust system for
alignment and leaks.

F-9.
Muffler Removal and Replacement
Disconnect the support bracket and clamps on each
side of the muffler. Loosen the
tail
pipe support
clamp
bolt and
pull
the
tail
pipe to the
rear
until

it
is free of the muffler. Remove the muffler. To

install
the muffler, reverse the above
steps
and

properly
align the complete system, then tighten
connecting support brackets securely. Operate the engine and check for possible leaks.
F-10.
Tail
Pipe Removal and Replacement
Refer
to
Figs.
F-l,
F-2 and
F-3.

Disconnect the support bracket and clamps both at the
rear
of the muffler and also at outlet end of
the
tail
pipe.
Free
the
tail
pipe from the muffler. To
assemble, position
tail
pipe to the muffler and secure clamps, being careful to align the exhaust
system so it doesn't contact body or frame.
Check

system for exhaust gas leaks.

F-ll.
EXHAUST SYSTEM SPECIFICATIONS
EARLY
MODEL
HURRICANE
F4
ENGINE
EARLY
MODEL
DAUNTLESS
V-6
ENGINE

TYPE:

Muffler:
Type

Exhaust
Pipe:

Wall
Thickness

Tail
Pipe:

Crossover
Pipe
Diameter
Single

Reverse
Flow

1.625*
[4,13 cm.] .065* [1,6 ram.]

1.625*
[4,13 cm.] Single
With
Cross-Over

Reverse
Flow
2.00* [5,08 cm.] .065* [1,6 mm.]
2.00* [5,08 cm.]
2.00* [5,08 cm.] .065* [1,6 mm.]

Wall
Thickness Single
With
Cross-Over

Reverse
Flow
2.00* [5,08 cm.] .065* [1,6 mm.]
2.00* [5,08 cm.]
2.00* [5,08 cm.] .065* [1,6 mm.]

LATE
MODEL
HURRICANE
F4
ENGINE
LATE
MODEL
DAUNTLESS
V6
ENGINE

TYPE:
Muffler:

Exhaust
Pipe:
Wall
Thickness

Exhaust
Pipe Extension:

Wall
Thickness

Crossover
Pipe: Single

Reverse
Flow
2.005* [5,09 cm.]

1.755*
[4,46 cm.]

1.625*
[4,13 cm.]
.065* [1,6 mm.]

1.629*
[4,14 cm.] 2.00* [5,08 cm.] .065* [1,6 mm.] Single with
Cross-Over

Reverse
Flow
2.005* [5,09 cm.]

1.755*
[4,46 cm.]
2.00* [5,08 cm.] .065* [1,6 mm.]
2.00* [5,08 cm.] .065* [1,6 mm.]

1.753*
[4,45 cm 1

Wall
Thickness

Tail
Pipe
1.753*
[4,45 cm.] Single with
Cross-Over

Reverse
Flow
2.005* [5,09 cm.]

1.755*
[4,46 cm.]
2.00* [5,08 cm.] .065* [1,6 mm.]
2.00* [5,08 cm.] .065* [1,6 mm.]

1.753*
[4,45 cm 1 141

'Jeep'
UNIVERSAL SERIES SERVICE
MANUAL

Fl
EXHHUST
EMISSION
CONTROL
SYSTEM

Contents

HURRICANE
F4-134
ENGINE
SUBJECT
PAR.

GENERAL
Fl-1

AIR
PUMP
Fl-2

PUMP
AIR
FILTER
Fl-3

AIR
DELIVERY
MANIFOLD
Fl-4

AIR INJECTION TUBES.
Fl-5

ANTI-BACKFIRE
DIVERTER
VALVE.
.Fl-6

ENGINE
COMPONENTS
. .Fl-7
Carburetor
. .Fl-8

Distributor
........
.Fl-9
Exhaust
Manifold Fl-10

MAINTENANCE
Fl-11
Carburetor
Fl-12,
Fl-13

Distributor
Fl-14

Anti-Backfire
Diverter
Valve.
.........
.Fl-15

Check
Valve Fl-16

Fl-1. GENERAL—F4-134
Engine

The
Hurricane
F4-134
engine
Exhaust
Emission
Control
System consists of a belt driven air pump

which
directs compressed air through connecting

hoses
to a steel distribution manifold into stainless steel injection
tubes
in the exhaust port adjacent
to each exhaust valve stem.
This
air with its normal

oxygen
content, reacts with the hot but incom­
pletely burned exhaust
gases
and permits further combustion in the exhaust port or manifold.
Fl-2. 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 ex­
haust system temperatures.

Fl-3. PUMP
AIR
FILTER

The
air filter attached to the pump is a replaceable
element type constructed of conventional pleated
paper
with steel end plates.

The
filter should be replaced every
12,000
miles
[19,200
km.] under normal conditions or sooner

under
adverse weather or driving conditions.

Fl-4.
AIR
DELIVERY
MANIFOLD

The
air delivery manifold, constructed of cold
rolled
steel with a zinc plating, distributes the air

from
the pump to each of the air delivery
tubes

in
a uniform manner.

A
check valve is attached to the air delivery
SUBJECT
PAR.

Air
Pump Fl-17
Carburetor
Air Cleaner Fl-18

REMOVAL PROCEDURES
.Fl-19
Air
Pump
Fl-20
Anti-Backfire
Diverter Valve Fl-21
Air
Distribution Manifold,
And
Air Injection Tubes
Fl-22

REQUIRED
EQUIPMENT
.Fl-23

REPLACEMENT
PARTS
Fl-24

WARRANTY
Fl-25

DIAGNOSIS
GUIDE
Fl-26
MAINTENANCE CHART
Fl-27

CARBURETOR SPECIFICATIONS
Fl-28

DISTRIBUTOR SPECIFICATIONS
Fl-29
SPARK PLUG
GAP
.Fl-30

manifold.
Its function is to prevent the reverse flow
of exhaust
gases
to the pump should the pump
drive
fail.
This
reverse flow would damage the air
pump and connecting
hose.

Fl-5.
AIR
INJECTION
TUBES

The
air injection
tubes
of stainless steel are inserted
into machined
bosses
of the exhaust manifold. The

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

Fl-6.
ANTI-BACKFIRE DIVERTER VALVE

The
anti-backfire diverter valve prevents
engine
backfire
by briefly interrupting the air being in­
jected into the exhaust manifold during periods of deceleration (rapid throttle closure).

Fl-7.
ENGINE
COMPONENTS

The
following items
vary
in design or specifications

from
those
on vehicles not equipped with the Ex­
haust Emission
Control
System.

Fl-8.
Carburetor

A
carburetor with a specific flow characteristic is used for exhaust emission control.

A
carburetor dashpot is provided to control the throttle closing speed.

Fl-t.
Distributor

The
ignition distributor used with the exhaust emission system requires a different advance curve

from
that used on the F4-134
engine
prior
to the
introduction of exhaust emission systems. 143

Fl
EXHAUST EMISSION CONTROL SYSTEMS

12793

FIG.
Fl-1—HURRICANE
F4-134
ENGINE EXHAUST EMISSION CONTROL SYSTEM
1—
Anti-Backfire
Diverter
Valve

2— Air
Pump

3—
Pump
Air
Filter
Injection
Tube(s)
(Inside
Manifold)

5—Air
Delivery
Manifold
6—
Check
Valve
Ignition
timing must be set at 0 or at top dead
center.

Fl-10.
Exhaust Manifold

The
exhaust manifold is provided with a
boss
that is drilled and tapped at each cylinder to accept the

air
delivery manifold and injection tubes.

Fl-11.
MAINTENANCE

Efficient
performance of the exhaust emission con­
trol
system is dependent upon precise maintenance.
In
addition to the air pump and connecting
hoses

and
tubes, this system's efficiency is dependent
upon special carburetor calibration, distributor cen­

trifugal
advance curve and ignition timing setting

which
must be adjusted at 0 or top dead center.

Road
test
is a factory recommended optional serv­ ice every
6,000
miles
[9,600
km.] to evaluate over­

all
performance.

The
following procedure is recommended to assist
in
diagnosing performance and/or emission level
problems that are peculiar to
Exhaust
Emission

Control
System equipped vehicles.

Fl-12.
Carburetor

Check
carburetor number for proper application. (Specifications are listed at the end of this section)

Check
the dash pot and adjust as required.

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 and air
cleaner
in place. Adjust the throttle
stop
screw to
idle the
engine
at specified RPM. All lights and accessories must be turned off.

Fl-13.
Carburetor
Idle
Setting
NOTE:
The idle mixture adjustment procedure for
the late model
YF-4941S
and
YF-6115S
Carter
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 %
turn
to "Lean Best
Idle."
Refer
to Section E, Fig. E-6.

The
"Lean
Best
Idle"
method of idle setting is as follows:

a.
Any scheduled service of ignition system should
precede this adjustment. 144

'Jeep'
UNIVERSAL
SERIES SERVICE
MANUAL

Fl
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.
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 mixture
adjustment back out (counterclockwise-richer) un­

til
maximum
speed
is just regained at a "lean as
possible" mixture adjustment.

Fl-14.
Distributor

Check
the distributor number for proper appli­
cation.
Check
the distributor cam dwell angle and
point condition and adjust to specifications or re­ place as required. (Specifications listed at the end
of this section)
Check
ignition timing and set at

0°
or
TDC.

Fl-15.
Anti-iackfire
Diverter 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 to the check valve.
Accelerate the
engine
to allow the throttle to
close

rapidly.
The valve is operating satisfactorily if a
momentary interruption of rushing air is audible.

Fl-16.
Check Valve

The
check valve prevents the reverse flow of ex­
haust
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
distri­

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

Fl-17.
Air
Pump

Check
for proper drive belt tension with belt tension
gauge
W-283. The belt strand tension should be

50-60
pounds on a belt with previous service, meas­

ured
on the
longest
accessible span
between
two pulleys. When installing a new belt, adjust the
tension to
60-80
pounds tension. 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 the pump

outlet
opening. 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.

Fl-18.
Carburetor
Air
Cleaner

Every
6000
miles
[9,600
km.] clean the inside
sur­

face at 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.

More
frequent cleaning and replacement is advis­ able when the car is operated in dusty areas or on
unpaved roads. Accumulated dirt restricts air flow,
reducing fuel
economy
and performance.

Fl-19.
REMOVAL
PROCEDURES

The
following paragraphs
give
the procedures for removing the major units of the Exhaust Emission

Control
System and the required equipment
needed.

Fl-20.
Air
Pump

Loosen
the air pump adjusting strap to facilitate

drive
belt removal. Remove the air pump air dis­
charge hose(s) and air filter attachment. Separate
the air pump from its mounting bracket. At time of installation, 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
50-60
pounds on a belt
with previous service and
60-80
pounds on a new
belt.

Fl-21.
Anti-Backfire
Diverter Valve

The
anti-backfire diverter valve removal requires disconnecting the
hoses
and bracket to
engine
at­
taching screws.

Fl-22.
Air
Distribution
Manifold
and
Injection Tubes

In
order to remove the air distribution manifold
without bending the tubing, which could result in
fractures
or leakage, it is necessary to remove the
exhaust manifold as an assembly from the
engine.

After
the exhaust manifold assembly is removed
from
the
engine,
place the manifold in a vise and

loosen
the air distribution manifold
tube
retaining nuts at each cylinder exhaust port. Tap the injec­
tion
tubes
lightly to allow the air distribution mani­
fold to be pulled away partially from the exhaust manifold. The stainless steel injection
tubes
in the
exhaust manifold may have
become
partially fused
to the air distribution manifold and, therefore, may
require
application of heat to the joint in order to
separate. While applying heat to the joint, rotate
the injection
tubes
with pliers being careful not to
damage the
tubes
by applying excessive force.

At
time of installation, the air injection
tubes
must
be positioned into the exhaust manifold prior to
placing the exhaust manifold assembly on the en­ gine.

Note:
Two different length injection
tubes
are used.

The
shorter length injection
tubes
must be inserted into cylinders 1 and 4. 145

Fl

EXHAUST
EMISSION CONTROL SYSTEMS The
air distribution manifold should be installed
after the exhaust manifold assembly is torqued
to the cylinder head. The recommended procedure
for exhaust manifold assembly installation is as follows:
Clean
the mating surface of both the
manifold and cylinder head.
Install
the exhaust manifold to the cylinder head using a new gasket.

Tighten
the manifold to cylinder head, attaching
bolts
down evenly.
Finish
torque tightening to 29
to 35 ft. lbs. [3,4 a 4,8 kg-m.].

Fl-23.
REQUIRED
EQUIPMENT

Each
station licensed to perform repair and main­
tenance on the Exhaust Emission Control System
must be equipped with that equipment necessary
for major
engine
tune-up analysis which shall in­ clude at least the following or equivalent.
Ignition Analyzer Oscilloscope
Ammeter
Ohmmeter
Voltmeter Tachometer
2 Vacuum Gages

Pressure
Gage (0-10 psi.)

Cam
Angle Dwell Meter Ignition Timing
Light

Engine
Exhaust Combustion Analyzer Compression Tester

Fl-24.
REPLACEMENT
PARTS

Parts
necessary to repair and/or maintain the

Exhaust
Emission Control System are available through any Jeep
SALES CORPORATION
ware­
house.

Fl-25.
WARRANTY

All
parts of the Exhaust Emission Control System

are
covered by the Manufacturer's Warranty as stated in the Warranty Service and 'Jeep' Quality
Maintenance Plan booklet.

Fl-26.
EXHAUST EMISSION CONTROL
SYSTEM
DIAGNOSIS GUIDE
Pump Noisy

Hoses Touching Other Parts of Engine or Body (Hood).

Note:
The air pump is not completely noiseless.

Under
normal conditions, pump
noise
rises in pitch as
engine
speed
increases. It is also desirable to
allow for normal break-in wear of the pump prior
to replacement for excessive noise.

Pump Seized

Replace
pump.

Leak
In
Hose

Check
for leaks; using
soap
and water — tighten
clamps or replace
hoses.
Pump
Inoperative

Loose Belt — tighten belt — do not pry on housing.

Filter
Plugged — replace.

Exhaust Backfire

Check
for vacuum leaks — correct as necessary.
Check
air filter for excessive
restriction
— replace as necessary.

Check
anti-backfire valve — replace as necessary.

Induction System Backfire

Verify
engine
timing and distributor dwell.

Verify
accelerator pump charge. 146

'Jeep'
UNIVERSAL SERIES
SERVICE
MANUAL

Fl
Fl-27.
EXHAUST EMISSION CONTROL SYSTEM MAINTENANCE CHART

Efficient
performance of the Exhaust Emission
Control
System is
dependent
upon precise main­tenance. As indicated in the following chart, it is very important that all of the maintenance require­

ments
listed are performed with extreme care at
the specific intervals indicated.

OPERATION
Thousands of miles* or
number of months whichever
occurs first 2
6
12 18
24 30

R R
R R
R R

O O o O
O
o O

R
O
o
o

R
o

o o

o
o

o
O
o
Inspect engine-driven
belts
for condition and tension...
Replace positive crankcase ventilation valve (PCV) Replace filter on exhaust emission control system

Clean
carburetor air cleaner

Engine
tune-up
Check
engine
timing

Adjust
carburetor idle
speed
and mixture

Perform
factory-recommended road
test
for evaluation of overall performance and handling

R
— Required Services
O
— Optional Services
Miles
2,000

6,000

12,000
18,000
24,000
30,000
Kilometers

3,200

9,600

19,200
28,800
38,400 48,000

Fl-28.
EXHAUST EMISSION CONTROL SYSTEM CARBURETOR SPECIFICATIONS

Make
Models

Part
Number
Throttle
Bore
Main
Venturi

Low
Speed Jet

Main
Metering Jet

Idle
Port
Nozzle Bleed in Body
Pump Jet

Float
Level
Dash
Pot Setting

Engine
Idle
RPM:
with Distributor Model
IAY-4401A.
with Distributor Model
IAY-4401B.
Carter
— Single Bore

^ an H
YF
4366S ana 4941S, 6115S

1M"
[3,81 cm.]

IX"
[3,18 cm.]
.035"
[0,889
mm.] .089" [2,26 mm.]
.184" x .030" [4,70 a
0,765]
.028"
[0,713
mm.]
.024"
[0,610
mm.] lW [6,74 mm.]
%"
[3,75 mm.] 650 — 700 700 — 750

Fl-29.
EXHAUST EMISSION CONTROL SYSTEM DISTRIBUTOR SPECIFICATIONS

Engine

Make
Models
Rotation
Point Opening

Breaker
Lever
Tension..
Cam
Angle (Dwell)
Condenser Capacity
Dist.
Degrees and RPM:
Start..

Intermediate

Maximum

TIMING:
Crankshaft

Mark
Location

Firing
Order
F4-134
Prestolite

IAY-4401A

CCW
Rotor End
.020"
[0,508
mm.|
17 — 20 ozs. [482 a 567 gr.l
42°

.25 — .28 mfd.

0°
— 300
3°
— 375

13.5°
— 1700

0°
TDC @ Idle

Crankshaft
Pulley
1-3-4-2
Prestolite

IAY-4401B

CCW
Rotor End
.020"
[0,508
mm.]
17 — 20 ozs. [482 a 567 gr.
42°

.25 — .28 mfd.

0°
— 450

4.5°
— 550

13.5°
— 1700

0°
TDC @ Idle

Crankshaft
Pulley
1-3-4-2

Fl-30.
SPARK PLUG
GAP

Spark
Plug Gap. .030"
[0,765
mm.] 147

Fl

EXHAUST
EMISSION
CONTROL
SYSTEMS
IMPORTANT
NOTICE

The
Exhaust
Emission Systems covered
in
this publication
meet
State and

Federal
requirements for hydrocarbon and carbon
monoxide
emissions.

To
assure continued proper operation,
these
systems
must
be
inspected

regularly,
parts must be replaced
at
factory-recommended intervals and
engine

tune-up services performed at intervals specified in the
Exhaust
Emission
Con­
trol
System Maintenance charts.

For
the
above
reasons,
these
systems
must not, under any circumstances,
be

altered
to anything other than
required
specifications provided in this publication.

Further,
the
Exhaust
Emission
Control
System, or any
of
its components, must
not be physically altered or modified in any respect.

DHTfl
TAG

For
the serviceman's guidance, each vehicle equipped with exhaust emission

control
will
have data
tag
permanently affixed
to the
radiator shroud—-in
example:

VEHICLE
EMISSION
CONTROL
INFORMATION
MODEL
F4-134
C.I.D.

•
ENGINE
AT
NORMAL
OPERATING
TEMPERATURE

•
LIGHTS
AND
ALL
ACCESSORIES OFF

•
IDLE
MIXTURE
. . .
LEAN
BEST
IDLE

•
IGNITION
TIMING
0*
(TDC)
•
SPARK
PLUG
GAP
. . . .030

•
DWELL
...
42* (.020
POINT
GAP)
•
IDLE
SPEED
. . .
700-750 RPM
TRANSMISSION
IN
NEUTRAL
DURING
TUNE
UP

SEE SERVICE MANUAL
FOR
ADDITIONAL INFORMATION
THIS VEHICLE CONFORMS
TO U.S.
DEPT.
OF
H.E.W.
REGULATIONS APPLICABLE
TO
1971 MODEL YEAR NEW MOTOR VEHICLES

Jeep
CORPORATION
14401

Important:
Always refer
to
the data tag when checking or re-adjusting ignition

timing,
idle speed, and idle mixture. 148

'Jeep'
UNIVERSAL SERIES SERVICE
MANUAL

Fl
EXHAUST
EMISSION
CONTROL
SYSTEM

Contents

DAUNTLESS
V-6
ENGINE
SUBJECT
PAR.

GENERAL
.F2-1
HEATED
AIR
SYSTEM.
. F2-2
Testing
Thermo
Air
Cleaner
F2-4
Positive
Crankcase
Ventilation
Valve.
. . .F2-6

Vacuum
Motor Replacement . .F2-8
Air
Cleaner Sensor Replacement F2-9
Replacement Procedures F2-7

AIR
PUMP
.F2-10

AIR
FILTER.
F2-11

AIR
DELIVERY
MANIFOLD.
F2-12

AIR INJECTION TUBES.
F2-13

ANTI-BACKFIRE
VALVE..
.F2-14
ENGINE COMPONENTS
.F2-15
MAINTENANCE
.F2-3
Carburetor
F2-16, F2-17

Distributor
F2-18

Anti-Backfire
Valve . . F2-19
Check
Valve..
F2-20

F2-1.
GENERAL
—V-6
Engine

The
Dauntless V-6
engine
Exhaust
Emission
Con­

trol
System consists of a belt-driven air pump

which
directs compressed air through connecting
hoses
to a steel distribution manifold into stainless steel injection
tubes
in the exhaust port adjacent
to each exhaust valve.
This
air, with its normal
oxygen
content, reacts with the hot but incom­
pletely burned exhaust
gases
and permits further combustion in the exhaust port or manifold.

The
Exhaust
Emission System on V6-225
engines

limits
the hydrocarbon and carbonmonoxide emis­sions from the exhaust system. The system includes

an
engine
designed for low emissions and lean
carburetor
calibration at idle and part throttle.

The
lean carburetion is possible because of the
heated air system that is part of the Emission
System.
See Fig. F2-2.
With
the heated air system
operating, inlet air temperature is around
115°F.
[46°C],
after the first few minutes of operation.

This
makes the use of lean (hot weather)
cali­
bration
possible, and the vehicle
still
responds and

drives
well in cold weather.

The
engine
has a "ported"
spark
advance, with the

vacuum
take-off just above the throttle valve, so that there is no vacuum advance at closed throttle,
but there is vacuum advance as
soon
as the throttle is opened slightly. To reduce emissions at idle and
at lower
engine
speeds, the
engine
timing is such
that the distributor
will
not have centrifugal ad­
vance until about 900 RPM.
F2-2.
HEATED
AIR
SYSTEM

The
heated air system on late model V6 engines,
consists of a manifold heat collector, a heated-air
SUBJECT
PAR.

Air
Pump F2-21
Intake
Manifold F2-22
Carburetor
Air Cleaner F2-5, F2-23

REMOVAL PROCEDURES
F2-24
Air
Pump. F2-25
Anti-Backfire
Valve..
. . .F2-26
Air
Distribution Manifold,

And
Air Injection Tubes F2-27

REQUIRED
EQUIPMENT..
. F2-28
REPLACEMENT
PARTS..
.F2-29

WARRANTY
F2-30
DIAGNOSIS GUIDE
F2-31
MAINTENANCE CHART.
F2-32
GENERAL
SPECIFICATIONS
F2-33

CARBURETOR SPECIFICATIONS.
.... .F2-34

DISTRIBUTOR SPECIFICATIONS
. .F2-35
SPARK PLUG GAP
F2-36
pipe, a adapter elbow and an air cleaner contain­ing temperature control doors operated by vacuum
through a temperature sensor. The heat
stove
is a
sheet
metal cover, shaped to and bolted on with
the right exhaust manifold. Air drawn in along the lower
edge
of the
stove
passes across the mani­
fold surface, picking-up heat. The heated air is
drawn
out from the front of the manifold, through
the heated air pipe and adapter elbow into the
snorkel
of the air cleaner.

The
temperature control air cleaner is designed to mix this heated air with cold air from under the
hood so that carburetor inlet air temperature aver­
ages
about
115°F.
[46°C.].
This
mixing is
done
by two air doors, a cold air door and a hot air door,

which
move
together
so that when the cold air door is closed, the hot air door is open and vice
versa.
Most of the time, both doors
will
be partially
open as required to control the temperature. When
the underhood temperature reaches about 135
°F
[57°C]
the cold air door
will
open wide and the
hot air door
will
close
tight See Fig. F2-3. Ob­ viously, if underhood temperatures rise above
135°F.
[57°C]
the air cleaner
will
no longer be
able to control temperatures and the inlet air tem­

perature
will
rise with underhood temperature.
The
temperature doors are moved by a diaphragm
type vacuum door. When there is no vacuum pres­ ent in the motor, the diaphragm spring forces the
cold air door open and the hot air door closed.

Whenever
the
engine
is running, the amount of
vacuum
present in the vacuum motor depends on
the temperature sensor in the air cleaner which is located in the vacuum line
between
the intake
manifold and the vacuum motor. In the sensor, a 149

EXHAUST
EMISSION
CONTROL
SYSTEMS

bi-metal temperature sensing spring starts to open

a
valve to bleed more air into the vacuum line
whenever the temperature in the air cleaner rises
above about
115°F.
[46°C.].
Whenever the tem­

perature
falls below about
115°F.
[46°C]
the sensing spring starts to
close
the air bleed into the

vacuum
line, allowing more manifold vacuum to

reach
the vacuum motor. Whenever there is 9 inches [22,8 cm.] or more of vacuum in the vacuum
motor, the diaphragm spring is compressed, the cold air door is closed and the hot air door is
opened.

When
the
engine
is not running, the diaphragm
spring
will
always hold the cold air door open and
the hot air door closed. However, when the
engine

is running, the position of the doors depends on the

air
temperature in the air cleaner.
When
starting a cold
engine
(air cleaner tempera­
ture under 95° F. [35°
C.]),
the cold air door
will
close
and the hot air door
will
open immediately. See Fig. F2-4.
This
is because the air bleed valve

in
the sensor is closed so that
full
manifold vacuum
is applied in the vacuum motor. The cold air door

will
remain tightly closed only a few minutes, how­
ever. As
soon
as the air cleaner starts receiving
hot air from the heat
stove,
the sensor
will
cause the cold air door to open partially, mixing cold air

with
the hot air as necessary to regulate air cleaner temperature within 20° of the ideal
115°F.
[46°C]

air
inlet temperature. See Fig. F2-5.
If
underhood air temperature rises to 135° F.
[57°
C] the air to the vacuum bleed valve in the
sensor
will
be wide open so that vacuum motor approaches zero. The diaphragm spring in the vac­
uum
motor
will
hold the cold air door wide open

and
close
the hot air door tightly. If underhood
temperature rises above 135° F. [57° C]
car­
buretor inlet air temperature
will
also rise above
135°
F. [57° C.].

While
air cleaner temperature is being regulated, 150