6 Y -3 0 EN G INE ELECTRICAL
1,000 ENG. RPM
2,000 ENG. RPM
Fig. 5 i— Ig n itio n S p a r k vs E n g in e S pe e d
higher the engine speed, the more the weights throw out
and the further the breaker cam is advanced. See Fig. 6i.
The centrifugal advance required varies considerably
between various engine models. In order to determine
the advance for a given engine, the engine is operated
on a dynamometer at various speeds with a wide-open
throttle. Spark advance is varied at each speed until the
range of advance that gives maximum power is found.
The cam assembly, weights and springs are then selected
to give this advance. Timing, consequently, varies from
no advance at idle to full advance at high engine speed
where the weights reach the outer limits of their travel.
Vacuum Advance
Under part-throttle operation a high vacuum develops in
the intake manifold and a smaller amount of air and
gasoline enters the cylinder. Under these conditions,
additional spark advance (over and above advance
provided by the centrifugal advance mechanism) will
Fig. 6i—Centrifugal Advance Mechanism
increase fuel economy. In order to realize maximum
power, ignition must take place still earlier in the cycle.
To provide a spark advance based on intake manifold
vacuum conditions, many distributors are equipped with
a vacuum advance mechanism. The mechanism has a
spring-loaded diaphragm connected by linkage to the
distributor. The spring-loaded side of the diaphragm is
air-tight, and is connected in many cases by a vacuum
passage to an opening in the carburetor. See Fig.
l i .
This
opening is on the atmospheric side of the throttle when
the throttle is in the idling position. In this position,
there is no vacuum in the passage.
When the throttle is partly opened, it swings past the
opening of the vacuum passage. Intake manifold vacuum
then can draw air from the air-tight chamber in the
vacuum advance mechanism and this causes the
diaphragm to be moved against the spring. This motion
is transmitted by linkage to the distributor breaker
assembly rotation is governed by the amount of vacuum
in the intake manifold up to the limit imposed by the
design of the vacuum advance mechanism.
When the distributor breaker plate assembly is rotated,
the contact points are carried around the breaker cam to
an advanced position, so that the breaker cam contacts
the rubbing block and closes and opens the points earlier
in the cycle. This provides a spark advance based on the
amount of vacuum in the intake manifold. Thus, for
varying compressions in the cylinder the spark advance
will vary, permitting greater economy of engine
operation. It should be recognized that the additional
advance provided by vacuum control is effective in
providing additional economy only on PART-THROT-
TLE operation.
At any particular engine speed there will be a certain
definite advance resulting from operation of the
LIGHT DUTY TRUCK SERVICE MANUAL
Содержание Light Duty Truck 1973
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Страница 39: ...HEATER AND AIR CONDITIONING 1A 13 Fig 14 Heater Wiring Diagrams LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 53: ...HEATER AND AIR CONDITIONING 1A 27 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 115: ...LIGHT DUTY TRUCK SERVICE M A N U A L HEATER AND AIR CONDITIONING 1A 89...
Страница 123: ...BODY 1B 3 Fig 6 Typical 06 Van LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 149: ...BODY 1B 29 Fig 84 Body Mounting 06 Fig 85 Body Mounting 14 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 171: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 2 Frame Horizontal Checking Typical FRAME 2 3...
Страница 173: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 4 10 30 Series Truck Frame FRAME 2 5...
Страница 174: ...2 6 FRAME LIGHT DUTY TRUCK SERVICE MANUAL Fig 5 Underbody Reference Points G Van...
Страница 177: ...LIGHT DUTY TRUCK SERVICE MANUAL G 10 20 C 10 P 10 30 Fig 2 Front Suspension C P K Typical FRONT SUSPENSION 3 3...
Страница 185: ...FRONT SUSPENSION 3 11 Fig 16 Toe out on Turns LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 229: ...REAR SUSPENSION AND DRIVELINE 4 5 Fig 13 Rear Spring Installation C K Models LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 310: ...5 44 BRAKES C MODELS G MODELS P MODELS Fig 77 Parking Brake System LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 351: ...ENGINE 6 15 Fig ID Sectional View of Eight Cylinder Engine LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 375: ...EN G IN E 6 39 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 376: ...6 4 0 ENGINE LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 377: ...ENG IN E 6 41 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 378: ...LIGHT DUTY TRUCK SERVICE MANUAL Fig 37L K Series Engine Front Mount 6 42 ENG INE...
Страница 379: ...E N G IN E 6 43 FRONT MOUNT REAR MOUNT Fig 38L G Series Engine Mounts LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 400: ...6 6 4 ENG INE LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 401: ...ENG IN E 6 65 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 402: ...6 6 6 ENGINE LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 403: ...E NG IN E 6 67 Fig 36V C Series Engine Mounts LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 423: ...EN G IN E C OOLING 6K 13 Fig 16 Overheating Chart LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 424: ...6 K 1 4 ENG INE COOLING Fig 17 Coolant Loss Chart LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 455: ...ENGINE FUEL 6M 31 Fig K13 Accelerator Controls P30 42 454 Engine LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 456: ...6M 32 ENGINE FUEL Fig K15 Accelerator Controls G Van L 6 LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 506: ...CEC PLUNGER IS EXTENDED Fig lid Vacuum Advance Diagram Six Cylinder Engine 6T 14 EMISSION CONTROL SYSTEMS...
Страница 512: ...Fig 18e Vacuum Advance Diagram V8 Engine...
Страница 515: ...EMISSION CONTROL SYSTEMS 6T 23 Fig If Six Cylinder A I R System LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 516: ...6 T 2 4 E M IS S IO N CONTROL SYSTEMS LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 517: ...E M IS S IO N C O N TR O L SYSTEM S 6T 25 Fig 4f Diverter Valve Vent Valve LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 540: ...6 Y 1 2 ENGINE ELECTRICAL Fig 16b Battery Installation C K Series LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 572: ...6Y 44 ENGINE ELECTRICAL Fig 25i V 8 Spark Plug Wire Installation LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 592: ...7M 2 CLUTCHES MANUAL TRANSMISSIONS VIEW B Fig la Clutch Linkage Assy C K Models LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 593: ...CLUTCHES MANUAL TRANSMISSIONS 7M 3 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 594: ...7M 4 CLUTCHES MANUAL TRANSMISSIONS Fig lc Clutch Linkage Assy P Models LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 598: ...7M 8 CLUTCHES MANUAL TRANSMISSIONS LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 656: ...LIGHT DUTY TRUCK SERVICE MANUAL Fig 19M Drive Range Low First Gear Typical 7A 14 AUTOMATIC T R A N S M IS S IO N...
Страница 662: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 22M LI Range Manual First Gear Typical 7A 20 AUTOMATIC TRANSMISSION...
Страница 668: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 25M Reverse Range Typical 7A 26 AUTOMATIC T R A N S M IS S IO N...
Страница 739: ...FUEL TANKS AND EXHAUST 8 9 Fig 15 Filler Neck and Vent Hose Van LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 740: ...8 10 FUEL TANKS AND EXHAUST Fig 16 Fuel Feed and Return Pipes Front C K LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 743: ...FUEL TANKS AND EXHAUST 8 13 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 744: ...8 14 FUEL TANKS AND EXHAUST LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 746: ...8 16 FUEL TANKS AND EXHAUST Fig 2 5 Fuel Feed Pipe Front P 105 4 2 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 760: ...8 30 FUEL TANKS AND EXHAUST Fig 40 Exhaust Pipe P Models LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 761: ...FUEL TANKS AND EXHAUST 8 31 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 763: ...FUEL TANKS AND EXHAUST 8 33 LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 781: ...STEERING 9 15 OIL PRESSURE OIL RETURN PORT VALVE BODY Fig 21 Left Turn Position LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 832: ...LIGHT DUTY TRUCK SERVICE MANUAL Fig 106 Power Steering Pump Mounting Typical 9 66 STEERING...
Страница 833: ...PUMP ASSEMBLY STEERING GEAR TYPICAL SMALL V8 TYPICAL LARGE V8 STEERING 9 67...
Страница 860: ...9 94 STEERING LEAKAGE AREAS Fig 133 Power Steering Gear Leakage LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 861: ...STEERING 9 95 Fig 134 Power Steering Pump Leakage LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 886: ...11 10 CHASSIS SHEET METAL LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 891: ...ELECTRICAL BODY AND CHASSIS 12 5 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 897: ...ELECTRICAL BODY AND CHASSIS 12 11 Fig 14 Instrum ent Cluster Assembly C K Models LIGHT DUTY TRUCK SERVICE MANUAL...
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