E M I S S I O N C O N T R O L S Y S T E M S
6 T - 2 7
COMBUSTION PIPE ASSEMBLY
Fig. 8f—Diverter Valve Operation
The check valves used in this system are nothing more
than one-way valves which prevent exhaust gases from
entering and damaging the air injection pump, if for any
reason (such as drive-belt failure) the pump becomes
inoperative. Under normal operating conditions, air
pressure from the pump is sufficient to prevent exhaust
gases from entering the pump.
One (1) check valve is used per combustion pipe
assembly. L
-6
engines use one combustion pipe assembly
and thus one check valve. V
-8
engines use two
combustion pipe assemblies (one per bank) and thus two
(
2
) check valves.
AIR PUMP
The 2-vane pump is used in all applications to compress
the fresh filtered air and inject it into the exhaust
manifold or cylinder head. Pump components and
operation are described in the following text.
Pump Components (Fig. 9f)
1. Pump housing.
2. Centrifugal filter.
3. Set (2) of vanes which rotate about the centerline of
pump housing bore.
4. Rotor which rotates on axis that is different than
the centerline of the pump bore or the axis of vane
rotation. The rotor drives the vanes and is driven
by the pump pulley.
5. Set of seals (two per vane) which provide sealing
between the vanes and rotor.
The pump vanes are located 180° apart and are in
constant contact (or rather near contact) with the pump
Fig. 9f—Air Injection Pump Components
housing bore. The vanes are driven by the rotor and
slide through the slits in the rotor.
As the vane rotates past the inlet port, it provides an
increasing volume which has the effect of producing a
vacuum which draws air into the pump (Fig. lOf).
As the vane continues to rotate the other vane has also
passed the inlet port. At this point, the air that was
drawn into the pump is entrapped between these two
vanes. As the vanes continue to rotate the entrapped air
is carrier into a smaller volume and thus compressed.
Continuing rotation takes the vane past the outlet port.
Once the vane is past the outlet port, the compressed air
is exhausted out the port into the remainder of the
system.
Although the discussion has been concentrated on only
one cycle, it should be noted that actually two cycles are
made with every complete revolution.
As mentioned, the two-vane pump uses a centrigugal
filter to clean the air as it enters the inlet port of the
pump. This centrifugal filter actually opposes air entry
into the pump but is not efficient enough to hamper it.
This opposing force does, however, discharge any
foreign particles in the air from entering the pump.
The air enters the pump by passing past the vanes of the
centrifugal filter. The vanes of the filter are being
rotated at a relatively high r.p.m. These rotating vanes
hit any foreign particles in the air trying to enter the
pump and rebound them out and away from the pump
(Fig. Ilf).
DIVERTER VALVE
The purpose of the dirverter valve in the system is to
momentarily exhaust (divert) the air pumps output so
that it does not reach the exhaust valve area during the
initial stages of engine overrun (Fig. 12f). During engine
overrun; there is a high vacuum state just beneath the
carburetors throttle plate drawing rich mixtures of fuel
into the cylinders. This rich mixture cannot be
completely burned in the power stroke so much of it is
exhausted out the exhaust valves. If air from the pump
was allowed to combine with this mixture, a backfire
would occur. The diverter valve diverts the air pump
output at this time as follows:
CENTRIFUGAL
FILTER
AXIS OF
ROTOR
PUMP
ROTATION
USING
VANE
ROTOR
CENTERLINE OF PUMP BORE
AND AXIS OF VANE ROTATION
VIEW
PUMP
HOUSING
OUTLET
INLET
VANE
SEALS
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...
Page 642: ......
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...
Page 864: ......
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...
Page 934: ......
Page 942: ......
Page 970: ......
Page 972: ......
Page 974: ......
Page 976: ...V...
Page 978: ......
Page 979: ......