1967 CHEVROLET CAMARO air filter

ENGINE FUEL 6M-9

4.
Wash body with cleaning solvent and wip dry.

5. Wash filter element by sloshing up and down in

cleaning solvent.

6. Dry filter unit with an air hose or let stand until

dry.

7. Fill body of cleaner to full mark with SAE 50 engine

oil. If expected temperatures are to be consistently

below freezing, use SAE 20 engine oil.

8. Assemble filter and cover assembly to body of

cleaner.

9. Install cleaner, making sure it fits tight and is set

down securely. \

OIL
WETTED
PAPER
ELEMENT

Replacement

1.
Remove wing nut, washer and cover.

2.
Remove paper element and discard.

3.
Remove bottom section of air cleaner and gasket

on air horn of carburetor. Discard air horn gasket.

4.
Clean bottom section of air cleaner and cover pieces

thoroughly, to remove dust and grime.

NOTE:
Check bottom section of air cleaner

seal for tears or cracks.

5. Install a new gasket on carburetor air horn and set

bottom section of air cleaner on carburetor.

6. Install new paper element on bottom section of air

cleaner with either end up.

NOTE:
Plastisol seal is the same material on

both ends.

7. Install cover, washer and wing nut.

Testing (Fig. 5A)

Tool J-7825, is designed to check paper element air

cleaners to determine whether the element has ma-

terially decreased in efficiency arid should be replaced

or has only slightly increased air restriction and is

suitable for further service. In combination with a

tachometer, this instrument will quickly and accurately

determine the air cleaner element condition.

VENT HOLE

TOWARD DASH
NOTE:
t Before testing, inspect for holes or

breaks in the element, as these defects re-

quire immediate replacement. If no holes or

breaks exist, proceed as follows:

1.
Remove all hoses and plug all openings except air

cleaner inlet.

2.
Install air cleaner, using Tool J-7825 in place of the

wing nut. Screw Tool J-7825 onto the stud until it

seals tightly against the air cleaner cover. Rotate

the entire tool so that the scale can be read from

the left side of the car. Be sure the vent hole is

toward the dash.

3.
Connect a tachometer and place it so that it may be

read simultaneously with Tool J-7825.

4.
Zero oil level in the inner tube by pulling inner tube

upward until the rubber seal is above the vent hole,

then raise or lower as' required until the inner tube

oil level is exactly to the "0" mark.

5. Start engine. If engine is cold, allow to run for 2 to

3 minutes. The automatic choke must be fully open.

6. Accelerate the engine slowly until the inner tube oil

level of Tool J-7825 just reaches the 1/4 mark.

Allow engine speed to stabilize and note tachometer

(rpm) reading. Decelerate engine.

7. If the tachometer reading is at or below the follow-

ing, the oil wetted paper air cleaner element is re-

stricted beyond the allowable limit and should be

replaced. If testing indicates that the element

restriction is satisfactory at 12,000 miles, the ele-

ment need not be replaced but should be retested

every 6,000 miles thereafter until replaced.

Engine

Displacement

283 cu.
in.

327 cu.
in.

350 cu. in.

396 cu.
in.

427 cu.
in.
Horsepower

195

210

275

300

325

350

295

325

350

385

390

425
Minimum

Allowable

RPM

2300

2100

210Q

2600

2600

1550

1950

1850

1850

2140

Fig.
5A—Testing Air Cleaner
8. Remove tachometer and Tool J-7825 from vehicle

and push down inner tube until seal is below vent

hole to prevent oil loss.

Tool J-7825

FiHing
Tool

Tool J-7825 is shipped dry and must be filled with the

red gauge oil (specific gravity .826) provided.

Pull the knurled inner tube completely out of the gauge

and add oil to the reservoir until the oil level is between

CHEVROLET CHASSIS SERVICE /MANUAL

SECTION 6T

AIR INJECTION REACTOR SYSTEM

INDEX

Page

General Description 6T-1

Maintenance Procedures 6T>1

Drive Belt. ...-..' 6T-1

Inspection 6T-1

, Adjustment . . 6T-1

Replacement 6T-1

Drive Pulley . . . . 6T-1

Replacement 6T-1

Pump Pulley ....................... 6T-1

Replacement. 6T-1

Air Manifold, Hose and Tube
...........>*.
6T-2

Inspection . . 6T-2

Replacement 6T-2

Check Valve (s) 6T-3
Page

Inspection 6T-3

Replacement . . 6T-3

Mixture Control Valve 6T-3

Inspection 6T-3

Replacement 6T-3

Air Injection Tube 6T-4

Inspection . . . ... . . . .... 6T-4

Replacement 6T-4

Air Injection Pump 6T-4

Inspection 6T-4

Replacement . 6T-4

Pressure Relief Valve Replacement 6T-4

Special Tools 6T-5

GENERAL

The Air Injection Reactor (A.I.R.) System (fig. 1) con-

sists of: the air injection pump (with necessary brackets

and drive attachments), air injection tubes (one for each

cylinder), a mixture control valve, check valves (one for

In Line engines, two for V8 engines) and air manifold as-

semblies, tubes and hoses necessary to connect the

various components.

Carburetors and distributors for engines with the

A.I.R. System are designed, particularly, for these en-

gines;
therefore, they should not be interchanged with or

replaced by a carburetor or distributor designed for an

engine without the A.I.R. System.

The air injection pump (fig. 2) picks up fresh filtered

air from the air cleaner, compresses the air and injects

it through the air manifolds, hoses and injection tubes

into the exhaust system in the area of the exhaust valves.

The fresh air ignites and burns the unburned portion of

the exhaust gases in the exhaust system, thus minimizing

exhaust contamination.

The mixture control valve (fig. 3) when triggered by a

sharp increase in manifold vacuum, supplies the intake

manifold with fresh filtered air to lean out the fuel-air
DESCRIPTION

mixture and prevent exhaust system backfire.

The check valve(s) prevent exhaust gases from entering

and damaging the air injection pump, as back flow can

occur even under normal operating conditions.

When properly installed and maintained, the A.I.R.

System will keep exhaust emissions well below require-

ments. However, if any A.I.R. component or any engine

component that operates in conjunction with the A.I.R.

system should malfunction, the exhaust emissions might

be increased.

Because of the relationship between "Engine Tune

Up"
and "Unburned Exhaust Gases", the condition of

Engine Tune Up should be checked whenever the A.I.R.

System seems to be malfunctioning. Particular care

should be taken in checking items that affect fuel - air

ratio such as the crankcase ventilation system, the

carburetor and the carburetor air cleaner.

Because of the similarity of many parts, typical illus-

trations and procedures are used except where specific

illustrations or procedures are necessary to clarify the

operation. For Repair Procedures on the Air Injection

Pump,
refer to the Passenger Chassis Overhaul Manual.

MAINTENANCE PROCEDURES

Drive Belt

Inspection

• Inspect drive belt for wear, cracks or deterioration

and replace if required.

• Inspect belt tension and adjust if below 50 lb. using a

strand tension gauge.

Adjustment

• Loosen pump mounting bolt and pump adjustment

bracket bolt.

• Move pump until belt is tight (55±5 lb. used belt or

75±5 lb. new belt using a strand tension gauge) then

tighten adjustment bracket bolt and mounting bolt.

CAUTION: Do not pry on the pump housing.

Distortion of the housing will result in extensive

damage to the Air Injection Pump.

Replacement

• Loosen pump mounting bolt and pump adjustment
bracket bolt then swing pump until drive belt may be

removed.

• Install a new drive belt and adjust as outlined above.

Drive Pulley .

Replacement

• Remove drive belt as outlined above then replace

drive pulley.

• Install and adjust drive belt as outlined above.

Pump Pulley

Replacement

• Hold pump pulley from turning by compressing drive

belt then loosen pump pulley bolts.

• Remove drive belt as outlined above then remove

pump pulley.

• Install pump pulley with retaining bolts hand tight.

CHEVROLET CHASSIS SERVICE MANUAL

CLUTCH AND TRANSMISSIONS 7-33

from rolling. The pointer on the indicator quadrant

should line up properly with the range indicators in all

ranges.

OIL LEAKS

Before attempting to correct an oil leak, the actual

source of the leak must be determined. In many cases

the source of the leak can be deceiving due to "wind flow1 f

around the engine and transmission.

The suspected area should be wiped clean of all oil

before inspecting for the source of the leak. Red dye is

used in the transmission oil at the assembly plant and

will indicate if the oil leak is from the transmission.

The use of a "black light"* to identify the oil at the

source of leak is also helpful. Comparing the oil from

the leak to that on the engine or transmission dip stick

(when viewed by black light) will determine the source

of the leak.

Oil leaks around the engine and transmission are gen-

erally carried toward the rear of the car by the air

stream. For example, a transmission "oil filter tube

to case leak" will sometimes appear as a leak at the

rear of the transmission. In determining the source of

an oil leak it is most helpful to keep the engine running.

The mating surfaces of servo cover, converter housing,

transmission case and transmission case extension

should be carefully examined for signs of leakage. The

vacuum modulator must also be checked to insure that

the diaphragm has not ruptured as this would allow trans-

mission oil to be drawn into the intake manifold. Us-

ually, the exhaust will be excessively smoky if the

diaphragm ruptures due to the transmission oil added to

the combustion. The transmission case extension rear

oil seal should also be checked. All test plugs should be

checked to make sure that they are tight and that there

is no sign of leakage at these points. The converter

underpan should also be removed. Any appreciable quan-

tity of oil in this area would indicate leakage at the pump

square seal ring, pump seal assembly, or pump bolt

sealing washers.

BASIC PRESSURE CHECKS

Four basic pressure checks are used for diagnosis and

operational checks for the Aluminum Powerglide trans-

mission. All checks should be made only after thoroughly

warming up the transmission.

• Wide Open Throttle Upshift Pressure.

• Idle Pressure in "Drive" Range.

• Manual "Low" Range Pressure.

• "Drive" Range Overrun (Coast) Pressure.

It is not recommended that stall tests be conducted

which would result in engine vacuum falling below 10" Hg.

Pressure gauge hose connections should be made at

the low servo apply (main line) test point (fig. 14PG).

Run the gauge line into the driving compartment by

pushing aside the mast jacket seal. The line out of the

way of the drivers feet and connect to pressure gauge

J-21867.

• Wide Open Throttle Upshift Pressure Check

Refer to the pressure check chart for upshift pressure
SERVO APPLY

PRESSURE

Fig.
14PG - Pressure Test Plug

points as indicated on the lower servo apply (main line)

gauge.

• Idle Pressure in "Drive" Range

In addition tp the oil pressure gauges, a vacuum gauge

is needed for this check.

With the parking brake applied and the shift selector

lever in "Drive", low servo apply (main line) pressure

should be as shown on the pressure check chart.

If pressures are not within these ranges, the following

items should be checked for oil circuit leakage:

1.
Pressure regulator valve stuck.

2.
Vacuum modulator valve stuck.

3.
Hydraulic modulator valve stuck.

4.
Leak at low servo piston ring (between ring and

bore).

5.
Leak at low servo piston rod (between rod and bore).

6. Leak at valve body to case gasket.

7.
Leak at valve body gaskets.

8. Front pump clearances.

9. Check passages in transmission case for porosity.

• Manual "Low" Range Pressure Check

Connect a tachometer, apply the parking brake, place

the selector lever in "Low" range, and adjust the engine

speed to 1000 rpm with the car stationary.

Low servo apply (main line) pressure should be as

shown on the pressure check chart.

Pressures not within this range can indicate the fol-

lowing possibilities:

1.
Partially plugged oil suction screen.

2.
Broken or damaged ring low servo.

CHEVROLET CHASSIS SERVICE MANUAL

ACCESSORIES 15-2

GENERAL DESCRIPTION

The Cruise Master is a speed control system which

employs engine manifold vacuum to power the throttle

Servo unit. The Servo moves the throttle when speed

adjustment is necessary by receiving a varying amount

of bleed air from the Regulator unit. The Regulator

varies the amount of bleed air through a valve system

which is linked to a speedometer-like mechanism. The

speedometer cable from the transmission drives the

Regulator, and a cable from the Regulator drives the

instrument panel speedometer. The. engagement of the
Regulator unit is controlled by an Engagement Switch

located at the end of the turn signal lever. Two brake

release switches are provided: an Electric Switch dis-

engages the Regulator unit and a Vacuum Switch de-

creases the vacuum in the Servo unit to quickly return

the throttle to idle position.

The operation of each unit of the system and the

operation of the entire system under various circum-

stances is described below. Figure 1 shows the location

of the system components within the vehicle-

COMPONENT OPERATION

ENGAGEMENT SWITCH

This switch, located within the turn signal knob, has

three positions. In the fully released position, the switch

passes current through resistance wire to effect a "hold

in" magnetic field in the Regulator solenoid. This cur-

rent is sufficient only to hold the solenoid in place once

it has been actuated by the "pull in" circuit. Depressing

the button partially allows current to flow to the Regu-

lator solenoid at full voltage which causes the solenoid

to pull in. Depressing the button fully opens the circuit

to both the resistance and standard solenoid feed wires

and the solenoid becomes de-activated.

During vehicle operation the three switch positions

have the following functions:

Released

a. System not engaged: No function of the system

will occur although a small current is flowing

through the solenoid via the resistance wire (at

vehicle speeds over 20 mph).

b.
System engaged: The small current flowing

through the resistance wire is holding the solenoid

in the engaged position.

^r-WIRE RELIEF LUG

1 ^-#2-BLUE WIRE

L'3.BLACK WIRE
X /-TURN SIGNAL LEVER

SWITCH—^
^SN

RETAINING RING-^ %^

BUTTON -^

Fig.
2 - Cruise Master Engagement Switch
Partially Depressed

Full voltage is applied to the solenoid (vehicle speed

over 20 mph) which sets the Regulator to maintain the

vehicle speed at the time of Regulator engagement.

Fully Depressed

No electricity flows to the solenoid and the Regulator

is inactive. This position is used by the driver when he

desires to raise or lower his controlled speed. He may

accelerate to his new speed, press the button fully (Regu-

lator releases previously set speed) and release the but-

ton. Upon releasing the button, it passes through the

partially depressed position and the solenoid is "pulled

in", then into released position which provides "hold in"-

current. The driver may also press the button fully with

no pressure on the accelerator pedal. In this case the

regulator releases control of the throttle which returns

to idle and the car slows. When the button is released

the solenoid is pulled in and held in respectively and the

regulator resumes speed control at the speed of the

vehicle during the moment of button release (at vehicle

speeds over 20 mph).

LOCK
NUT

ORIFICE
TUBE

AND
CONNECTOR

ASSEMBLY

AIR FILTER AND

SOLENOID HOUSING COVER

Fig. 3 - Regulator Unit

CHEVROLET CHASSIS SERVICE MANUAL

ACCESSORIES 15-4

Fig. 5 - Servo Mounting

and the air bled into the chamber again equals the air

bled out. A balance occurs again with the diaphragm in

a new position. If the Regulator begins to supply more

bleed air, (vehicle speed increasing) the vacuum in the

chamber drops and the diaphragm moves away from the

vacuum port, withdrawing the tapered needle from the

orifice and enlarging it. Since the vacuum orifice is

now larger, the greater quantity of air being bled into

the chamber may be bled out by vacuum and a balance

again occurs with the diaphragm in a new position.

AIR

TO SERVO

VACUUM

TO SERVO
VACUUM

RELEASE

SWITCH

ELEaRIC

RELEASE

SWITCH

Fig.
6- Servo, Regulator and Hose
Fig. 7 - Release Switches and Brackets

REGULATOR

The Regulator is a device which has two primary

functions: First, it is a vacuum switch which, when en-

gaged by the driver, supplies engine manifold vacuum to

the Servo. Second, it meters a small variable quantity

of air to the Servo unit in order to change the carburetor

throttle opening to effect speed control. A secondary

function of the Regulator is to drive the speedometer.

Since the car speed is sensed by a speedometer-like

mechanism within the unit, the speedometer cable from

the transmission drives the Regulator which drives a

second cable (at a one to one ratio) to the speedometer.

The Regulator is electrically engaged and disengaged

through operation of the Engagement Switch and the

Electric Brake Release Switch. It has two sub-assem-

blies which make up the unit: one being the magnetic

speed sensing assembly and the other being the solenoid

actuated vacuum switch, air bleed and filter, and low

limit speed switch assembly (fig. 8 and 9).

Magnetic Speed Sensing Assembly

The speed sensing assembly operates in the same man-

ner as a speedometer unit except that instead of rotating

a needle through an angle proportional to the vehicle

speed, it rotates a rubber drum which is clutched to the

air bleed valve when the system is in operation. The

assembly is driven by the speedometer cable from the

transmission which turns a disk shaped ferrite magnet.

Facing the magnetic disk is the driven brass disk mounted

on a shaft with the rubber drum mounted on the same

shaft. A spiral hairspring connects the shaft to the

housing and allows it to rotate through an angle which is

proportional to car speed. If the car doubled its speed,

the shaft would rotate to twice its previous angle as may

be seen by noting the operation of a speedometer. The

CHEVROLET CHASSIS SERVICE MANUAL

driven disk is sandwiched between the magnetic disk and

a field plate. The field plate forms a returning path for

the magnetic field from the magnetic disk.

The gear drive for the magnetic disk is a 90 degree

nylon gear drive with the driven gear rotating both the

magnetic disK and the speedometer drive cable.

Vacuum Switch, Air Bleed and Filter, and Low

Limit Speed Switch

The end of the shaft from the speed sensing assembly

with the rubber drum extends into the air bleed metering

assembly. This rubber drum has a tang extending from

its surface which allows a set of points to close at a

specific car speed. When the car reaches about 20 mph,

the rubber drum has rotated far enough (moved by the

brass driven disk in the magnetic field) so that its tang

has allowed a spring loaded electrical point to contact

another point. These points are in series with the sole-

noid coil so that under 20 mph, no Regulator operation

is possible.

Surrounding the rubber drum is a "U" shaped spring

clip which is held spread away from the drum by the

nose or cam of the solenoid when the solenoid is in the

relaxed position. The rubber drum and this clip com-

prise the speed clutch of the regulator. When the sole-

noid is energized, the solenoid nose moves toward the

drum and releases the ends of the clip. The clip springs

inward and attaches itself by friction to the drum. Now,
ACCESSORIES 15-5

any change in car speed will rotate the drum and move

the "U" clip just as a speedometer moves its needle.

The top of the MUtf clip is attached to the air bleed valve.

The clip moves a sleeve which slides on the orifice

tube thereby covering and uncovering air ports in the

wall of the tube (the tube inner end is plugged) whenever

car speed changes from the speed at which the solenoid

was energized. The direction of drum rotation is such

that resulting bleed valve operation will cause the Servo

to decrease engine power if the car exceeds the preset

speed and increase engine power if car speed decreases.

The air which passes out the orifice tube enters the

Regulator through the openings in the solenoid housing,

passes through the oil wetted polyurethane filter, and then

enters the orifice tube ports.

When the solenoid is de-energized, the nose retracts

and cams the ends of the "U" clip outward so that it re-

leases the rubber drum.

The solenoid also operates a vacuum switch simul-

taneously with the clutching and declutching of the "U"

clip.
The vacuum switch supplies the Servo unit with

manifold vacuum. The solenoid operated vacuum valve

slides over two ports in the Regulator wall. One port

is connected to manifold vacuum and the other is con-

nected to the center port of the Servo unit. When the

solenoid is de-energized, the valve closes the manifold

vacuum port and opens the Servo port to the inside of

the regulator case. When the solenoid is energized, the

valve connects the Servo port to the manifold vacuum

AAAGNET

SPEED CUP

FIELD PLATE

HAIRSPRING
TO SPEEDOMETER

MAGNET HOUSING

ASSEMBLY
ORIFICE TUBE &

CONNECTOR ASSEM.
CONTROL

VALVE

CLUTCH

SPRING

LOW LIMIT

SPEED SWITCH

RUBBER

DRUM

VACUUM PORT

TO SERVO

INPUT CONNECTION

SOLENOID COIL

SOLENOID AND CLUTCH

HOUSING ASSEMBLY
VACUUM PORT

TO ENGINE

VACUUM VALVE

UNLOCKING CAM

•SOLENOID PLUNGER

AIR FILTER

SIDE VIEW SECTION

REGULATOR DISENGAGED
END VIEW SECTION

ENGAGED

Fig.
8 - Regulator-Cross Section '

CHEVROLET CHASSIS SERVICE MANUAL

ACCESSORIES
15-6

port thereby supplying vacuum to the Servo unit.

During system operation
the
following events occur:

1.
Car
speed below
20
mph—no function
of the
unit

because
the
rubber drum
has
not rotated
far
enough

to close
the
solenoid points.
No
energizing current

can flow through the solenoid coil.

2.
Car
speed above
20
mph—The tang
on the
rubber

drum
has
closed
the
solenoid points
and
current
is

flowing through
the 40 ohm
resistance wire
to the

solenoid coil. This current
is
not sufficient to "pull

in", the solenoid.

3.
Driver partially presses Engagement Switch—full

voltage flows through
the
solenoid
to
pull
it
into

operation. Solenoid
cam
tension
on the "U"
clip
is

released and the clip grips the rubber drum. Simul-

taneously the vacuum switch operates; applying man-

ifold vacuum
to the
Servo unit which tightens
the

throttle chain. When
the
driver releases pressure

from
the
accelerator pedal
the
unit will position the

throttle
to
maintain the speed
at
the time
of
solenoid
operation.

Driver releases
the
Engagement Switch—current

flows
to the
solenoid through
the 40
ohm wire and

since the solenoid is "pulled in", the reduced current

flow
is
sufficient to hold
it
in position.

The
car
begins
to
ascend
a
hill—car speed drops

slightly (very slightly) and the magnetic force on the

driven disk
of the
speed sensor
is
decreased.
The

disk rotates slightly
(as
would
a
speedometer shaft

because
of
hairspring tension) turning
the
rubber

drum. Since
the "U"
clip
is
gripping
the
drum,
it

moves
the
slide which COVERS
the air
bleed ports

more. With less air bleeding into the Servo, greater

vacuum exists
in it
and the diaphragm moves toward

the vacuum port opening
the
throttle wider.
The

tapered needle moves into the orifice further and the

diaphragm balances
in a
new position with the wider

throttle opening.
Car
speed
has
been maintained

automatically.

1.
Speedometer Cable

Adapter (From

Transmission)

2.
Gasket

3. Speedometer Cable

Adapter
(To

Speedometer)

4.
Adapter
and
Magnet

Housing

5. Rotating Magnet

6. Helical Ramp
7. Field Plate Adjusting

Pinion

8. Adjusting Pinion

Locating Spring

9. Brass Magnetically

Driven Disk

10.
Field Plate

11.
Hair Spring

12.
Hair Spring Keeper

13.
Rubber Drum

Tang
14.
Rubber Drum

1$.
"U"
Shaped Clutch

Spring

16.
Air
Bleed Sleeve

17.
Orifice Tube

18.
Orifice

19.
Orifice Tube Locknut

20.
Clutch
and
Solenoid

Housing

21.
Vacuum Supply Port

(To Servo)
22.
Vacuum Port (To

Intake Manifold)

23.
Vacuum Valve Slide

24.
Solenoid Coil

25.
Solenoid Plunger

Return Spring

26.
Solenoid Cover Gasket

27.
Air Filter

28.
Solenoid Cover

29.
Air Inlets

Fig.
9-
Regulator
-
Exploded

CHEVROLET CHASSIS SERVICE MANUAL

ACCESSORIES 15-9

Adjustment- Adjust the bead chain so that it is as tight

as possible without holding the throttle open when the

carburetor is set at its lowest idle throttle position.

When connecting the bead chain (engine stopped) manually

set the fast idle cam at its lowest step and connect the

chain so that it does not hold the idle screw off the cam.

If the chain needs to be cut, cut it three beads beyond the

bead which pulls the linkage.

REGULATOR

Service - A defective regulator, that is one which is not

simply out of adjustment, must be replaced. During re-

placement, check the hoses which connect to the regulator

and replace any which are cracked or deteriorated.

Air Filter

The air filter located in the solenoid cover should be

cleaned and re-oiled at engine oil change intervals.

1.
Snap the solenoid cover off.

2.
Remove the filter and wash it in kerosene or mineral

spirits. Squeeze it dry and wet with SAE 10 engine

oil.
Squeeze out excess oil and reinstall into the

cover.

3.
Attach the cover with neoprene seal to the solenoid

housing. Be certain that the cover fits tightly to the

housing.

One regulator adjustment is possible: Engagement-

Cruising Speed Zeroing (to remove any difference be-

tween engagement and cruising speed).

NOTE:
No regulator adjustment should be

made, however, until the following items have

been checked or serviced:

1.
Bead chain properly adjusted.

2.
All hoses in good condition, properly attached, not

leaking, not pinched or kinked.

3.
Regulator air filter clean and properly oiled.

4.
Electric and vacuum release switches properly

adjusted.

Engagement—Cruising Speed Zeroing

If the cruising speed is lower than the engagement

speed, loosen the orifice tube locknut and turn the tube

outward; if higher, turn the tube inward. Each 1/8 turn

will alter the engagement-cruising speed difference one

mph. Tighten the locknut after adjustment and check the

system operation at 50 mph.

ELECTRICAL SYSTEM CHECK OUT

1.
Check fuse and connector.

2.
Check electric brake switch as follows: Unplug con-

nector at brake switch. Connect ohmmeter at points

A and B on brake switch. The ohmmeter must indi-

cate infinity when the brake pedal is depressed and

continuity when pedal is released. The cruise re-

lease brake switch (electric) is adjusted as is the

standard stop light brake switch. Replace electric

brake switch if needed.

3.
Check engagement switch and connecting wiring as
follows: Unplug push button control connector

(brown, blue, black) at electrical wiring harness con-

nector and perform the following tests. (See Fig-

ure 10)

Test #1
—
Connect ohmmeter between terminal #1 (brown

wire) and terminal #2 (blue wire). Continuity shall be

maintained until switch is depressed all the way in.

Test #2
—
Connect ohmmeter between terminal #1 (brown

wire) and terminal #3 (black). No continuity shall be

shown; however, when the button is depressed halfway,

continuity shall be indicated. When the button is pressed

all the way down, no continuity shall be shown.

Test #3 — Connect ohmmeter between terminal #2 (blue

wire) and terminal #3 (black). Button released, no con-

tinuity; however, when the button is depressed partially

and fully, continuity shall be shown.

4.
Check regulator solenoid coil, low-speed switch, and

wiring harness as follows:

a. Disconnect engagement switch wire harness con-

nector from the main wire harness connector

(brown, blue, and black wires). Connect ohm-

meter
'
between point C (blue wire in main wire

harness) and ground. (Make sure the regulator is

well grounded to chassis.) The ohmmeter should

read 45 ohms ± 2 ohms. If a resistance of

greater value is shown, then disconnect the con-

nector from the regulator and measure the re-

sistance of the blue wire from point C to D. It

should measure 40 ohms. Check the resistance

from point E (vertical bar of terminal forming T)

to ground. It should measure 5 ohms ± 1/4 ohm.

Replace either the wiring harness or solenoid as

needed if greater values are indicated. The black

harness wiring from point F to G should also be

checked for continuity.

ENGAGEMENT SWITCH TEST

BUTTON POSITION

Cruise (released)

Engage (partially depressed)

Trim (fully depressed)
TERMINALS

1 TO 2

closed

Closed

open
1 TO 3

open

closed

open
2 TO 3

open

closed

closed

SERVO AND VACUUM SYSTEM CHECK OUT

To determine the condition of the diaphragm, remove

hoses from power unit and apply 14 inches of vacuum to

either vacuum tube opening (seal the other opening) and

hold in for one minute. The vacuum shall not leak down

more than 5 inches of vacuum in one minute. If leakage

is detected, replace servo. To utilize engine as a vac-

uum source, proceed as follows:

1.
DISCONNECT SERVO $EAD CHAIN and hoses from

servo and connect engine vacuum directly to vacuum

servo fitting (fitting in middle of servo). Seal the

servo unit opening.

2.
Note position of servo diaphragm.

3.
Start engine - the diaphragm should pull in.

4.
Clamp off engine vacuum supply line and check for

leakage. '

The cruise release brake switch (vacuum) and connecting

hoses can likewise be checked using a vacuum pump.

CHEVROLET CHASSIS SERVICE MANUAL