6-2 ENGINE
enough force to remove the boot. Do not pull on plug
wire.
TEST COMPRESSION (FIG. 1)
The compression check is important because an engine
with low or uneven compression cannot be tuned
successfully. It is essential that improper compression be
corrected before proceeding with the engine tune up.
1. Remove air cleaner and block throttle and choke in
wide open position.
2. Hook up starter remote control cable and insert
compression gauge firmly in spark plug port.
CAUTION:
Whenever the engine is cranked
remotely at the starter, with a special jumper
cable or other means, the distributor primary
lead must be disconnected from the negative
post on the coil.
3. Crank engine through at least four compression
strokes to obtain highest possible reading.
4. Check and record compression of each cylinder.
5. If one or more cylinders read low or uneven, inject
about a tablespoon of engine oil on top of pistons
in low reading cylinders (through spark plug port).
Crank engine several times and recheck
compression.
• If compression comes up but does not necessarily
reach normal, rings are worn.
• If compression does not improve, valves are
burned, sticking or not seating properly.
• If two adjacent cylinders indicate low compres
sion 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.
NOTE: If a weak cylinder cannot be located
Fig. 1—Checking Compression
with the compression check, see “Cylinder
Balance Test” under “Additional Checks and
Adjustments” in this section.
SERVICE AND INSTALL SPARK
PLUGS (FIG. 2 )
1. Inspect each plug individually for badly worn
electrodes, glazed, broken or blistered porcelains
and replace plugs where necessary.
2. Clean serviceable spark plugs thoroughly, using an
abrasive-type cleaner such as sand blast. File the
center electrode flat.
3. Inspect each spark plug for make and heat range.
All plugs must be of the same make and number.
4. Adjust spark plug gaps to specifications using a
round feeler gauge.
CAUTIO N:
Never bend the center electrode to
adjust gap. Always adjust by bending ground
or side electrode.
5. If available, test plugs with a spark plug tester.
6
. Inspect spark plug hole threads and clean before
installing plugs. Corrosion deposits can be removed
with a 14 mm.x 1.25 SAE spark plug tap (available
through local jobbers) or by using a small wire
brush in an electric drill. (Use grease on tap to
catch chips.)
CAUTIO N:
Use extreme care when using tap to
prevent cross threading. Also crank engine
several times to blow out any material
dislodged during cleaning operation.
7. Install spark plugs and torque to specifications.
NOTE: The following are some of the
greatest causes of unsatisfactory spark plug
performance.
• Installation of plugs with insufficient torque to
fully seat.
• Installation of the plugs using excessive torque
which changes gap settings.
• Installation of plugs on dirty seat.
• Installation of plugs to corroded spark plug hole
threads.
8
. Connect spark plug wiring.
SERVICE IG N ITIO N SYSTEM
1. Remove distributor cap, clean cap and inspect for
cracks, carbon tracks and burned or corroded
terminals. Replace cap where necessary (fig. 3).
2. Clean rotor and inspect for damage or deteriora
tion. Replace rotor where necessary.
3. Replace brittle, oil soaked or damaged spark plug
wires. Install all wires to proper spark plug. Proper
positioning of spark plug wires in supports is
important to prevent cross-firing.
LIGHT DUTY TRUCK SERVICE MANUAL
Summary of Contents for Light Duty Truck 1973
Page 1: ......
Page 4: ......
Page 6: ......
Page 53: ...HEATER AND AIR CONDITIONING 1A 27 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 115: ...LIGHT DUTY TRUCK SERVICE M A N U A L HEATER AND AIR CONDITIONING 1A 89...
Page 123: ...BODY 1B 3 Fig 6 Typical 06 Van LIGHT DUTY TRUCK SERVICE MANUAL...
Page 149: ...BODY 1B 29 Fig 84 Body Mounting 06 Fig 85 Body Mounting 14 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 171: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 2 Frame Horizontal Checking Typical FRAME 2 3...
Page 173: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 4 10 30 Series Truck Frame FRAME 2 5...
Page 174: ...2 6 FRAME LIGHT DUTY TRUCK SERVICE MANUAL Fig 5 Underbody Reference Points G Van...
Page 185: ...FRONT SUSPENSION 3 11 Fig 16 Toe out on Turns LIGHT DUTY TRUCK SERVICE MANUAL...
Page 224: ......
Page 266: ......
Page 351: ...ENGINE 6 15 Fig ID Sectional View of Eight Cylinder Engine LIGHT DUTY TRUCK SERVICE MANUAL...
Page 375: ...EN G IN E 6 39 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 376: ...6 4 0 ENGINE LIGHT DUTY TRUCK SERVICE MANUAL...
Page 377: ...ENG IN E 6 41 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 378: ...LIGHT DUTY TRUCK SERVICE MANUAL Fig 37L K Series Engine Front Mount 6 42 ENG INE...
Page 400: ...6 6 4 ENG INE LIGHT DUTY TRUCK SERVICE MANUAL...
Page 401: ...ENG IN E 6 65 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 402: ...6 6 6 ENGINE LIGHT DUTY TRUCK SERVICE MANUAL...
Page 403: ...E NG IN E 6 67 Fig 36V C Series Engine Mounts LIGHT DUTY TRUCK SERVICE MANUAL...
Page 410: ......
Page 423: ...EN G IN E C OOLING 6K 13 Fig 16 Overheating Chart LIGHT DUTY TRUCK SERVICE MANUAL...
Page 424: ...6 K 1 4 ENG INE COOLING Fig 17 Coolant Loss Chart LIGHT DUTY TRUCK SERVICE MANUAL...
Page 456: ...6M 32 ENGINE FUEL Fig K15 Accelerator Controls G Van L 6 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 492: ......
Page 512: ...Fig 18e Vacuum Advance Diagram V8 Engine...
Page 516: ...6 T 2 4 E M IS S IO N CONTROL SYSTEMS LIGHT DUTY TRUCK SERVICE MANUAL...
Page 528: ......
Page 590: ......
Page 593: ...CLUTCHES MANUAL TRANSMISSIONS 7M 3 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 598: ...7M 8 CLUTCHES MANUAL TRANSMISSIONS LIGHT DUTY TRUCK SERVICE MANUAL...
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Page 654: ......
Page 743: ...FUEL TANKS AND EXHAUST 8 13 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 744: ...8 14 FUEL TANKS AND EXHAUST LIGHT DUTY TRUCK SERVICE MANUAL...
Page 760: ...8 30 FUEL TANKS AND EXHAUST Fig 40 Exhaust Pipe P Models LIGHT DUTY TRUCK SERVICE MANUAL...
Page 761: ...FUEL TANKS AND EXHAUST 8 31 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 763: ...FUEL TANKS AND EXHAUST 8 33 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 766: ......
Page 832: ...LIGHT DUTY TRUCK SERVICE MANUAL Fig 106 Power Steering Pump Mounting Typical 9 66 STEERING...
Page 833: ...PUMP ASSEMBLY STEERING GEAR TYPICAL SMALL V8 TYPICAL LARGE V8 STEERING 9 67...
Page 861: ...STEERING 9 95 Fig 134 Power Steering Pump Leakage LIGHT DUTY TRUCK SERVICE MANUAL...
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Page 876: ......
Page 886: ...11 10 CHASSIS SHEET METAL LIGHT DUTY TRUCK SERVICE MANUAL...
Page 891: ...ELECTRICAL BODY AND CHASSIS 12 5 LIGHT DUTY TRUCK SERVICE MANUAL...
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