Table Of Contents - Chevrolet Light Duty Truck 1973 Service Manual

valve still open, the cylinder continues to empty itself
because of this momentum.
On the compression stroke, the intake valve stays open
past bottom center because incoming gases will continue
to pack their way in for a short time after the piston
reverses direction, due to their momentum.
On the power stroke, the exhaust valve opens before
bottom center to get the exhaust gases started out of the
cylinder.
On the exhaust stroke, the intake valve opens before top
center to start the air fuel mixture moving into the
cylinder.
Valve timing is not variable with speed and load as is
ignition timing. Except for very small variations due to
the stack of tolerances in the valve train (Fig.
always open and close at the same time in the cycle.
There is, however, one particular speed for a given
engine at which the air-fuel mixture will pack itself into
the cylinders most effectively. This is the speed at which
the engine puts out its peak torque. At low engine
speeds, compression is somewhat suppressed due to the
slight reverse flow through the valves just as they open or
close, when the mixture is not moving fast enough to
take advantage of the time lag. At very high speeds, the
valve timing does not allow quite enough time during the
opening and closing periods for effective packing of the
air-fuel mixture into the cylinders.
General Description............................................................ 6-20
Component Replacement and Adjustment................. 6-20
Engine Assembly................................................................ 6-20
Removal (C, K and P Series).................................... 6-20
Removal (G Series)........................................................ 6-22
Installation (C, K and P Series)............................... 6-23
Installation (G Series)................................................... 6-24
Manifold Assembly........................................................... 6-25
Removal.............................................................................. 6-25
Installation......................................................................... 6-25
Rocker Arm Cover............................................................ 6-26
Removal.............................................................................. 6-26
Installation......................................................................... 6-26
Valve Mechanism............................................................... 6-26
Removal.............................................................................. 6-26
Installation and Adjustment........................................ 6-26
Valve Lifters........................................................................ 6-26
Locating Noisy Lifters.................................................. 6-27
Removal.............................................................................. 6-27
Installation......................................................................... 6-27
Valve Stem Oil Seal and/or Valve Spring.............. 6-27
D), valves
8
ENGINE MECHANICAL
IN-LINE ENGINES
INDEX
Cylinder Head Assemblies.............................................. 6-28
Oil P an .................................................................................. 6-28
Oil Pump............................................................................... 6-29
Oil Seal (Rear M ain)...................................................... 6-29
Torsional Damper.............................................................. 6-30
Crankcase Front Cover................................................... 6-31
Oil Seal (Front Cover).................................................... 6-32
Camshaft............................................................................... 6-33
Fig. 8D-Valve System Components
Replacement...................................................................... 6-27
Removal............................................................................... 6-28
Installation......................................................................... 6-28
Removal............................................................................... 6-28
Installation......................................................................... 6-28
Removal............................................................................... 6-29
Installation......................................................................... 6-29
Replacement...................................................................... 6-29
Removal.............................................................................. 6-30
Installation......................................................................... 6-30
Removal.............................................................................. 6-31
Installation......................................................................... 6-31
Replacement...................................................................... 6-32
EN G IN E 6 -1 9
LIGHT DUTY TRUCK SERVICE MANUAL