Chevrolet 1974 Light Duty Truck User manual

FOREWORD
This manual includes theory of operation and procedures
for diagnosis, maintenance and adjustments, minor service
operations, and removal and installation for components of
Chevrolet Light Duty Trucks. Procedures involving dis
assembly and assembly of major components for these
vehicles are contained in the 1974 Chevrolet Passenger Car
and Light Duty Truck Overhaul Manual. Wiring diagrams for
1974 trucks are contained in a separate Wiring Diagram
Booklet.
The Section Index on the contents page enables the user to
quickly locate any desired section. At the beginning of each
section containing more than one major subject is a Table of
Contents, which gives the page number on which each major
subject begins. An Index is placed at the beginning of each
major subject within the section.
Summaries of Special Tools, when required, are found at
the end of major sections while specifications covering
vehicle components are presented at the rear of the manual.
This manual should be kept in a handy place for ready
reference. If properly used, it will enable the technician to
better serve the owners of Chevrolet built vehicles.
All information, illustrations and specifications contained
in this literature are based on the latest product information
available at the time of publication approval. The right is
reserved to make changes at any time without notice.

SECTION INDEX
1974
LIGHT DUTY
TRUCK
(SERIES 10-30)
CHASSIS SERVICE
MANUAL
SECTION NAME
0
GENERAL INFORMATION
AND LUBRICATION
1A
HEATER AND
AIR CONDITIONING
IB
BODY
2
FRAME
3
FRONT SUSPENSION
4-WHEEL DRIVE
4
REAR SUSPENSION
AND DRIVELINE
5
BRAKES
6
ENGINE
6K
ENGINE COOLING
6M
FUEL SYSTEM
6T
1MISSION CONTROL
SYSTEMS
6Y
ENGINE ELECTRICAL
7M
CLUTCH AND
MANUAL TRANSMISSION
7A
AUTOMATIC
TRANSMISSION
8
FUEL TANK AND
EXHAUST SYSTEM
9
STEERING
10
WHEELS AND TIRES
11
CHASSIS SHEET METAL
12
ELECTRICAL— BODY
AND CHASSIS
13
RADIATOR AND GRILLE
14
BUMPERS
15
ACCESSORIES
SPECIFICATIONS

#
SECTION 0
GENERAL INFORMATION AND LUBRICATION
CONTENTS OF THIS SECTION
General Information .................................................................. 0-1
Lubrication.................................................................................... 0-5
GENERAL INFORMATION
INDEX
Model Line Up............................................................... 0-1
Truck Model De ignation............................................. 0-1
Vehicle Identification Number and Rating Plate .... 0-1
Engine Number............................................................... 0-2
Unit and Serial Number Location ........................... 0-2
Service Part Identification Plate................................. 0-3
Key and Lock ............................................................... 0-3
Emergency Starting........................................................ 0-3
Towing............................................................................... 0-4
MODEL LINE UP
The 10 through 35 Serie truck model line-up for 1974
con i t of the model hown in the Chart in thi
ection.
Truck Model Design tion
A five digit number preceded by a letter i u ed to
de ignate truck model . For example, vehicle C 10703
would be: Conventional C, 4900 lb .-6800 lb . GVW 1,
42 in. -47 in. Cab-to-Axle dimen ion 07, Cha i cab 03,
a li ted below.
First Letter - Ch ssis
C - Conventional (Conventional Cab, Suburban)
G - Light Duty Forward Control
K - Four-Wheel Drive
P - Forward Control
First Number-GVW R nge
1 - 4500-7150 lb .
2 - 5500-8200 lb .
3 - 6200-14000 lb .
Second nd Third Numbers-
C b-To-Axle Dimension
05 - 30-35 in.
07 - 42-47 in.
08 - 48-53 in.
09 - 54-59 in.
10 - 60-65 in.
14 - 84-89 in.
Fourth nd Fifth Numbers-Body Styles
Pickup boxe , tailgate and drop gla , van bodie , and
trim are option .
03 - Cab
05 - Van (windowle )
06 - Suburban and Van (with window )
14 - Utility
32 - Motor Home Cha i
42 - Forward Control Cha i
63 - Four-Door Crew Cab
VEHICLE IDENTIFICATION NUMBER
AND RATING PLATE
A combination vehicle identification number and rating
plate u ed on all model (fig. 1) i located on the left
door pillar of CK model . On Forward Control model
(except P30 Motor Home Cha i ) it i attached to the
da h and toe panel.
The vehicle identification number tamped on the plate
decode into the information hown in Figure 2.
LIGHT DUTY TRUCK SERVICE MANUAL

0-2 GENERAL INFORMATION AND LUBRICATION
Fig. 1— Vehicle Identific tion Number nd R ting
Pl te Inform tion
Fig. 2— Vehicle Identific tion Number
ENGINE NUMBER
The engine number indicate manufacturing plant,
month and day of manufacture, and tran mi ion type.
A typical engine number would be F1210TFA, which
would breakdown thu :
F - Manufacturing Plant (F-Flint, T-Tonawanda)
12 - Month of Manufacture (December)
10 - Day of Manufacture (tenth)
T - Truck
FA - Tran mi ion and engine type
UNIT AND SERIAL NUMBER LOCATIONS
For the convenience of ervice technician and engineer
when writing up certain bu ine paper uch a
Warranty Report , Product Information Report , or
reporting product failure in any way, the location of the
variou unit number have been indicated. The e unit
number and their prefix or uffix are nece ary on the e
paper for variou rea on - uch a accounting, follow-
up on production, etc.
The prefixe on certain unit identify the plant in which
the unit wa manufactured and thereby permit proper
follow-up of the plant involved to get correction made
when nece ary.
Alway include the prefix in the number.
Axles
• Serie 10, 20 and P30 Code i tamped on Front of
Right Rear Axle Tube Inboard of Upper Control
Arm Bracket.
• Serie CG30 (except dual wheel) code i tamped at
the Forward Upper Surface of Carrier.
• Dual Wheel Part Number and Production Code i
tamped on Front of Right Axle Tube.
Tr nsmissions
• 3-Speed Tran mi ion Unit Number Located on
Lower Left Side of Ca e Adjacent to Rear of Cover.
• 4-Speed Tran mi ion Unit Number Stamped on
Rear of Ca e, Above Output.
• Turbo Hydra-Matic 350 Tran mi ion Unit Number
Located on Right Rear Vertical Surface of Oil Pan.
• The Turbo Hydra-Matic Tran mi ion 400 Serial
Number i Located on the Light Blue Plate on the
Right Side of the Tran mi ion.
Engines
• 6-Cylinder Engine Unit Number Located on Pad at
Right Hand Side of Cylinder Block at Rear of
Di tributor.
• 8-Cylinder Engine Unit Number Located on Pad at
Front, Right Hand Side of Cylinder Block.
Delcotrons
Delcotron Unit Serial Number Located at Top of
Rear Hou ing.
B tteries
Battery Code Number Located on Cell Cover Top of
Battery.
St rters
Starter Serial Number and Production Date
Stamped on Outer Ca e, Toward Rear.
DIVISION
C = CHEVROLET
T = GMT
ENGINE
DESIGNATION
Q = L6-250-1
T= L6-292-1
V = V8-
Y = V8-
Z = V8-
Q 1
CHASSIS TYPE
C = 2 WHEEL DRIVE
G=LIGHT DUTY
FORWARD CONTROL
K=4 WHEEL DRIVE
P =FORWARD CONTROL
BODY STYLE
2-Forw rd Control
ch ssis only
3-C b-ch ssis (Cut w y)
4-C b nd pickup box
5-Forw rd Control
ch ssis only
(Steel-Aluminum Body)
6-Suburb n body
7-Forw rd Control
(Rec. Vehicle Ch ssis)
8-Utility (Bl zer)
MODEL YEAR
4 = 1974 for ll
Series.
SEQUENTIAL NUMBER
ASSEMBLY PLANT
A-L kewood
B-B ltimore
C-Southg te
D-Dor ville
F-Flint <—
G-Fr mingh m
J-J nesville
K-Leeds
L-V n Nuys
N-Norwood
V-GM Truck-Ponti c
R-Arlington
S-St. Louis
T-T rrytown
U-Lordstown
W-Willow Run
Y-Wilmington
Z-Fremont
1-Osh w
2-Ste. Therese
LIGHT DUTY TRUCK SERVICE MANUAL

GENERAL INFORMATION AND LUBRICATION 0-3
SERVICE PARTS IDENTIFICATION
v .i.N .^ ^ ^ ^ H H H jw /B A S E H H H se|
V I N — VEHICLE IDENTIFICATION NUMBER
NO TE: TH E S PE CIA L EQ UIP MEN T LISTED BEL O W H AS BEEN IN STALLED ON
IMPORTANT: RETAIN THIS PLATE AS A PERMANENT RECORD
Fig. 3— Service P rts Identific tion Pl te
SERVICE PARTS IDENTIFICATION PLATE
The Service Part Identification Plate (fig. 3) i provided
on all Truck model . On mo t erie it will be located on
the in ide of the glove box door, or, on Forward Control
erie , it will be located on an inner body panel. The
plate li t the vehicle erial number, wheelba e, and all
Production option or Special Equipment on the vehicle
when it wa hipped from the factory including paint
information. ALWAYS REFER TO THIS INFORMATION
WHEN ORDERING PARTS.
KEYS AND LOCKS
Two key are provided with each vehicle. Different lock
cylinder operated by a eparate key are available a an
option for the liding ide load door and rear load door .
EMERGENCY STARTING
• Engine in vehicle with automatic tran mi ion
cannot be tarted by pu hing or towing the vehicle.
• Never tow a manual tran mi ion - equipped vehicle
to tart becau e the urge forward when the engine
tart could cau e a colli ion with the tow vehicle.
• A car with a di charged battery may be tarted by
tran ferring electrical power from a battery in
another car - called "jump tarting".
Jump St rting
The following procedure i for u e ONLY under the
following condition . Departure from the e condition
and procedure , could re ult in: (1) eriou per onal
injury (particularly to eye ) or property damage from
uch thing a battery explo ion, battery acid or electrical
burn , or (2) damage to electronic component in either
vehicle. If all the condition cannot be met, or if you are
uncertain about them, we trongly recommend for your
afety and that of your vehicle that you leave the tarting
to a competent mechanic.
• The battery in the other vehicle mu t be of the s me
nomin l volt ge, 12 volt , and mu t be neg tively
grounded. (All General Motor car , light truck
(10,000 GVWR and under), and motor home u e
12-volt, negatively grounded electrical y tem and
c n be u ed to jump tart one another.) The
nominal voltage and grounding of the other
vehicle’ battery may be determined by checking the
pecification in it owner’ manual. U e of a
boo ter battery of a higher nominal voltage, or
which i po itively grounded may re ult in eriou
per onal injury or property damage.
CAUTION: Never expose battery to open flame
or electric spark - battery action generates
hydrogen gas which is flammable and explo
sive. Don’t allow battery fl id to contact eyes,
skin, fabrics, or painted s rfaces - fl id is a
s lf ric acid sol tion which co ld ca se serio s
personal inj ry or property damage. Fl sh any
contacted area immediately with water. We r
eye protection such s industri l s fety
spect cles or goggles when working on or
ne r b ttery. Remove ring , metal watch
band and other metal jewelry before jump
tarting or working around a battery. Be
careful in u ing metal tool and equipment.
If uch metal hould contact the po itive
battery terminal (or metal in contact with it)
and any other metal on the vehicle, a hort
circuit may occur which could cau e per onal
injury. Batterie and battery acid hould
alway be kept out of reach of children.
Fig. 4— Booster B ttery C ble Ground Connection
L 6 ENGINE
V 8 ENGINE
LIGHT DUTY TRUCK SERVICE MANUAL

0-4 GENERAL INFORMATION AND LUBRICATION
To Jump St rt:
1. Po ition the two vehicle o they are not touching.
Set parking brake and place automatic tran mi ion
in "PARK" (neutral for manual tran mi ion) in
each vehicle. Al o turn off light , heater and all
other unnece ary electrical load .
2. Remove vent cap from both the boo ter and the
di charged batterie . Lay a cloth over the open vent
well of each battery. The e two action help reduce
the explo ion hazard alway pre ent in either
battery when connecting "live" boo ter batterie to
"dead" batterie .
3. Attach one end of one jumper cable to the po itive
terminal of the booster b ttery (identified by a red
color, " + " or "P" on the battery ca e, po t or
clamp) and the other end of ame cable to po itive
terminal of disch rged b ttery.
4. Attach one end of the remaining negative cable to
the negative terminal (black color, " or "N" of
the booster b ttery, and the other end to the engine
lift bracket on 6 cylinder model or the delcotron
mounting bracket on 8 cylinder model (do not
connect directly to neg tive post of dead battery) -
taking care that clamp from one cable do not
inadvertently touch the clamp on the other cable.
Do not lean over the battery when making thi
connection.
5. Start the engine in the vehicle that i providing the
jump tart (if it wa not running). Let run a few
minute , then tart the engine in the vehicle with
the di charged battery.
6. Rever e the above equence exactly when removing
the jumper cable . Rein tall vent cap and di po e
in a afe manner any cloth u ed to cover vent
well , a the cloth may have corro ive acid on
them.
PUSH STARTING
If your truck i equipped with a manual 3- peed or
4- peed tran mi ion, it can be tarted in an emergency
by pu hing. When being pu hed to tart the engine, turn
off all unnece ary electrical load , turn ignition to
"ON," depre the clutch pedal and place the hift lever
in high gear. Relea e the clutch pedal when peed
reache 10 to 15 mile per hour. Bumper and other part
contacted by the pu hing vehicle hould be protected
from damage during pu hing. Never tow the truck to
tart.
TOWING
All Except Four Wheel Drive Trucks
Normally your vehicle may be towed with all four wheel
on the ground for di tance up to 50 mile at peed of
le than 35 MPH. The engine hould be off and the
tran mi ion in neutral.
However, the rear wheel mu t be rai ed off the ground
or the drive haft di connected when the tran mi ion i
not operating properly or when a peed of 35 MPH or
di tance of 50 mile will be exceeded.
CAUTION: If a tr ck is towed on its front
wheels only, the steering wheel m st be sec red
with the wheels in a straight ahead position.
Four Wheel Drive Trucks
It i recommended that the truck be towed with the front
wheel off the ground. The truck can be towed, however,
with the rear wheel off the ground if there i damage in
the rear wheel area. In thi event, the tran mi ion
elector lever hould be placed in the "N" (neutral)
po ition and with conventional four wheel drive the
front drive di engaged. With Full Time four wheel drive
the tran fer ca e hould be in high. Towing peed
hould not exceed 35 MPH for di tance up to 50 mile .
If truck i towed on it front wheel , the teering wheel
hould be ecured to keep the front wheel in a traight
ahead po ition.
When towing the vehicle at low peed (approx. 20
MPH), for a very hort di tance only, the tran mi ion
mu t be in NEUTRAL and with conventional four wheel
drive the tran fer ca e MUST be in "TWO WHEEL
HIGH." With Full Time four wheel drive the tran fer
ca e hould be in high.
When towing the vehicle at fa ter peed for greater
di tance , the following tep MUST be taken:
• If front wheel are on the road, di connect the front
drive haft.
• If rear wheel are on the road, di connect the rear
drive haft.
STEEL TUBING REPLACEMENT
In the event that replacement of teel tubing i required
on brake line, fuel line, evaporative emi ion, and
tran mi ion cooling line , only the recommended teel
replacement tubing hould be u ed.
Only pecial teel tubing hould be u ed to replace brake
line. That i , a double wrapped and brazed teel tubing
meeting G.M. Specification 123 M. Further, any other
teel tubing hould be replaced only with the relea ed
teel tubing or it equivalent. Under no condition hould
copper or aluminum tubing be u ed to replace teel
tubing. Tho e material do not have ati factory fatigue
durability to with tand normal vehicle vibration .
All teel tubing hould be flared u ing the up et (double
lap) flare method which i detailed in Section 5 of thi
Manual.
LIGHT DUTY TRUCK SERVICE MANUAL

GENERAL INFORMATION AND LUBRICATION 0-5
VEHICLE LOADING
Vehicle loading 4mu t be controlled o weight do not
exceed the number hown on the Vehicle Identification
Number and Rating Plate for the vehicle.
In trailer hauling application , the vehicle rear end
weight at the ground with trailer attached mu t not
exceed the "Maximum Rear End Weight at Ground"
rating of the vehicle.
A typical example of a truck in a loaded condition i
hown in Figure 5. Note that the axle or GVW
capabilitie are not exceeded.
LOADED-MAXIMUM GVWR: 6000-LBS.
FRONT GAWR: 3250 LBS. REAR GAWR: 3582 LBS.
‘Front Curb 2100 lbs.
Front C rgo &
P ss. Lo d 400 lbs.
2500 lbs.
‘Re r Curb 1585 lbs.
Re r C rgo &
P ss. Lo d 1915 lbs-
3500 lbs.
TOTAL WEIGHT AT GROUND: 6000 lbs.
"Curb weight equ ls the weight of the vehicle without driver,
p ssenger or c rgo, but including fuel nd cool nt.
Fig. 5— Typic l Vehicle Lo ded Condition
LUBRICATION
INDEX
Maintenance Schedule ................................................. . 0-5
Engine.............................................................................. . 0-6
Oil and Filter Recommendation ............................ . 0-6
Drive Belt .................................................................... . 0-7
Po itive Crankca e Ventilation ................................ . 0-7
Air Injection Reactor Sy tem .................................. . 0-7
Controlled Combu tion Sy tem ............................... . 0-7
GM Evaporation Control Sy tem ........................... . 0-7
Manifold Heat Control Valve ................................. . 0-7
Air Cleaner................................................................... . 0-7
Fuel Filter..................................................................... . 0-7
Di tributor..................................................................... . 0-7
Governor....................................................................... . 0-7
Accelerator Linkage .................................................... . 0-7
Automatic Tran mi ion Fluid Recommendation . 0-7
Manual Tran mi ion
................................................... . 0-8
Tran mi ion Shift Linkage ....................................... . 0-8
Clutch...............................................................................
. 0-8
Rear Axle
Standard........................................................................ . 0-8
Propeller Shaft Slip Joint ......................................... . 0-8
Univer al Joint ............................................................. . 0-8
MAINTENANCE SCHEDULE
A eparate maintenance folder ha been provided with
each vehicle which contain a complete chedule and
brief explanation of the afety, emi ion control,
lubrication and general maintenance it require . The
Wheel Bearing
Front................................................................................ . 0-8
Rear.................................................................................
. 0-8
Brake Ma ter Cylinder................................................. . 0-9
Brake and Clutch Pedal Spring ............................... . 0-9
Parking Brake................................................................. . 0-9
Steering
Manual Steering Gear................................................ . 0-9
Steering Linkage and Su pen ion ........................... . 0-9
Hood Latch and Hood Hinge .................................... 0-9
Body Lubrication............................................................ 0-9
Four Wheel Drive
Propeller Shaft Centering Ball................................. . 0-10
Front Axle..................................................................... . 0-10
Air Vent Ho e.............................................................. . 0-10
Tran fer Ca e................................................................ . 0-10
Control Lever and Linkage...................................... . 0-10
Speedometer Adapter.................................................... . 0-10
Extended Vehicle Storage............................................ . 0-10
Lubrication Diagram
Conventional and Forward Control Model ......... . 0-17
Four Wheel Drive Model ........................................ . 0-18
1/2, 3/4 and 1 ton G Model
................................. . 0-19
maintenance folder information i upplemented by thi
ection of thi manual, a well a the eparate emi ion
control y tem folder al o furni hed with each vehicle.
Read all three publication for a full under tanding of
vehicle maintenance requirement .
LIGHT DUTY TRUCK SERVICE MANUAL

0-6 GENERAL INFORMATION AND LUBRICATION
The time or mileage interval for lubrication and
maintenance ervice outlined in thi ection are
intended a a general guide for e tabli hing regular
maintenance and lubrication period . Su tained heavy
duty and high peed operation or operation under
adver e condition may require more frequent ervicing.
ENGINE
Oil & Filter Recommend tions
The letter de ignation "SE" ha been e tabli hed to
corre pond with the requirement of GM 6136-M. "SE"
engine oil will be better quality and perform better than
tho e identified with "SA" through "SD" de ignation
and are recommended for all light-duty ga oline truck
regardle of model year and previou engine oil quality
recommendation .
Oil Ch nge Period
• U e only SE engine oil.
• Change oil each 4 month or 6,000 mile . If more
than 6,000 mile are driven in a 4-month period,
change oil each 6,000 mile .
• Change oil each 2 month or 3,000 mile , whichever
occur fir t, under the following condition :
—Driving in du ty condition
—Trailer pulling or camper u e.
—Frequent long run at high peed and high
ambient temperature .
—Motor Home u e.
—Stop and go type ervice uch a delivery truck ,
etc.
—Exten ive idling
—Short-trip operation at freezing temperature
(engine not thoroughly warmed-up).
• Operation in du t torm may require an immediate
oil change.
• Replace the oil filter at the fir t oil change, and
every econd oil change thereafter. AC oil filter
provide excellent engine protection.
The above recommendation apply to the fir t
change a well a ub equent oil change . The oil
change interval for the engine i ba ed on the u e of
SE oil and quality oil filter . Oil change interval
longer than tho e li ted above will eriou ly reduce
engine life and may affect the manufacturer’
obligation under the provi ion of the New Vehicle
Warranty.
A high quality SE oil wa in talled in the engine at
the factory. It i not nece ary to change thi
factory-in talled oil prior to the recommended
normal change period. However, check the oil level
more frequently during the break-in period ince
higher oil con umption i normal until the pi ton
ring become eated.
NOTE: Non-detergent and other low quality
oil are pecifically not recommended.
Oil Filter Type nd C p city
• Throwaway type, 1 quart U.S. mea ure, .75 quart
Imperial mea ure.
• 250 cu. in., 292 cu. in., AC Type PF-25. 350 cu. in.
454 cu. in., AC Type PF-35.
Cr nkc se C p city (Does Not Include Filter)
• 292 L6 Engine; 5 quart U.S. mea ure, 4.25 quart
Imperial mea ure.
• All other engine ; 4 quart U.S. mea ure, 3.25 quart
Imperial mea ure.
Recommended Viscosity
Select the proper oil vi co ity from the following chart:
RECOMMENDED SAE VISCOSITY NUMBER
10W, 5W-30, 10W-30, 10W-40
- 3 0 - 2 0 0 20 40 60 80 100
TEMPERATURE RANGE ANTICIPATED BEFORE NEXT OIL CHANGE, °F.
NOTE: SAE 5W-20 oil are not recommen
ded for u tained high- peed driving. SAE 30
oil may be u ed at temperature above 40°F.
SAE 5W-30 oil are recommended for all
ea on in vehicle normally operated in
Canada.
The proper oil vi co ity help a ure good cold and hot
tarting.
Checking Oil Level
The engine oil hould be maintained at proper level. The
be t time to check it i before operating the engine or a
the la t tep in a fuel top. Thi will allow the oil
accumulation in the engine to drain back in the
crankca e. To check the level, remove the oil gauge rod
(dip tick), wipe it clean and rein ert it firmly for an
accurate reading. The oil gauge rod i marked "FULL"
and "ADD OIL". If the oil i at or below the "ADD"
mark on the dip tick, oil hould be added a nece ary.
The oil level hould be maintained in the afety margin,
neither going above the "FULL" line nor below "ADD
OIL" line.
NOTE: The oil gauge rod i al o marked
"U e SE Engine Oil" a a reminder to u e
only SE oil .
Supplement l Engine Oil Additives
The regular u e of upplemental additive i pecifically
not recommended and will increa e operating co t .
However, upplemental additive are available that can
LIGHT DUTY TRUCK SERVICE MANUAL