Buick LeSabre 1965 Service Manual page 96

3 - 2 0 ADJUSTMENTS
ENGINE FUEL AND EXHAUST SYSTEMS
Figure 3-13—Right Exhaust Manifold and Valve Assembly - 300 Engine
shaft and bushings at both sides
of the flange. Allow the solvent
to soak for a few minutes, then
work the valve by rotating the
counterweight. Severe cases may
be freed by tapping endwise on
the shaft with a light hammer.
After the shaft is free, another
application of lubricant will as-
sure complete penetration of the
shaft bushings. See Figure 3-13.
e. Checking Manifold Valve
Thermostat Setting
The setting of the exhaust mani-
fold valve thermostat may be
ANTI-
RATTLE
SPRING
1/2 TURN
WIND-UP
Figure 3-14—Manifold Valve
Thermostat Wind-Up - 401
and 425 Engines
checked when the engine is at
room temperature of approxi-
mately 70°F. Unhook the outer
end of thermostat from anchor
pin on the manifold and hold the
valve in the closed position. To
bring the end of thermostat to the
anchor pin will then require ap-
proximately 1/2 turn wind-up of
the thermostat as shown in Figure
3-14.
The thermostat is not adjustable
and should never be distorted or
altered in any way as this will
affect its calibration. If the ther-
mostat does not have the proper
setting, or is damaged, it should
be replaced.
Fully open and fully closed posi-
tions of the e x h a u s t manifold
valve may be checked by the posi-
tion of the heavy section of the
manifold v a l v e weight. If the
heavy section is to the rear and
approximately 45 degrees up, the
valve is fully closed; if the heavy
section is forward and approxi-
mately 45 degrees up, the valve
is fully open. See Figure 3-15.
f. Positive Crankcase
Ventilator System
Service
All cars have a positive crank-
case ventilating system to help
WEIGHT
TO REAR-
VALVE
CLOSED
Figure 3-15—Manifold Heat Control
Valve Positions - 401 and
425 Engines
reduce air pollution and to pro-
vide more complete scavenging of
crankcase impurities. Ventilation
air is drawn in through the filter
in the filler cap on the left rocker
arm cover, down into the crank-
case, across and up into the right
rocker arm cover, up through the
ventilator valve, through a hose,
into the carburetor throttle body
and into the intake manifold. In-
take manifold vacuum draws any
fumes from the crankcase to be
burned in the engine.
When air flow through the carbu-
retor is high, added air from the
positive c r a n k c a s e ventilating
system has no noticeable effect on
engine operation; however, at idle
speed, air flow through the carbu-
retor is so low that any large
amount added by the ventilating
system would upset the air-fuel
mixture, causing rough idle. For
this reason, a flow control valve