Specifications

1-22
GROUP 1-ENGINES AND EXHAUST SYSTEMS
HIGH SPEED OPERATION
LOW INTAKE MANIFOLD VACUUM
TO
INTAKE
MANIFOLD
LOW SPEED OPERATION
HIGH INTAKE MANIFOLD VACUUM
TO
INTAKE
MANIFOLD
FROM
CRANKCASE
OUTLET
A1192-A
A1554-A
FIG. 8—Positive Crankcase Ventilation Regulator
Valve
FIG. 9-Cooling System
In the vent tube-type system, the
crankcase vapors are discharged to
the atmosphere. In the positive sys-
tem, the crankcase vapors are
directed to the intake manifold.
VENT TUBE-TYPE CRANKCASE
VENTILATION SYSTEM
A crankcase ventilation tube is lo-
cated at the rear of the engine. The
forward motion of the car causes a
partial vacuum to be formed at the
tube outlet. This vacuum action
causes air to be drawn through the
engine from the combination oil filler
and breather cap located in the front
of the valve push rod chamber cover
(Fig. 6). The filler cap contains a
maze filtering element.
Filtered air from the breather cap
flows into the front section of the
valve rocker arm shaft chamber.
Here the air has a chance to normal-
ize its temperature before contacting
contaminating vapors originating in
the crankcase. Warm ventilating air
minimizes the formation of crank-
case sludge.
The ventilating air moves down
past the push rods into the crankcase.
Air is diverted from the front section
of the crankcase through holes in the
front of the cylinder block wall to
ventilate the timing chain chamber.
The air from the crankcase is then
directed into the crankcase ventila-
tion tube by the rotating action of
the crankshaft.
POSITIVE CRANKCASE VENTILATION
SYSTEM
Ventilating air enters the engine in
the normal manner through the
breather cap and is distributed
through the engine in the same man-
ner as in the vent tube-type system.
However, instead of the ventilating
air being discharged to the atmos-
phere, it is directed to the intake
manifold. The air is directed to the
intake manifold through an exhaust
tube which extends from the crank-
case ventilation outlet in the left side
of the cylinder block to a spring-
loaded regulator valve (Fig. 7). The
valve regulates the amount of air to
meet changing operating conditions.
During idle, intake manifold vac-
uum is high. The high vacuum over-
comes the tension of the spring pres-
sure and seats the valve (Fig. 8). With
the valve in this position, all the
ventilating air passes through a cali-
brated orifice in the valve. With the
valve seated, there is minimum venti-
lation. As engine speed increases
and manifold vacuum decreases, the
spring forces the valve off its seat and
to the full open position. This in-
creases the flow of ventilating air.
COOLING SYSTEM
The coolant is drawn from the
bottom of the radiator by the water
pump which delivers the coolant to
the cylinder block (Fig. 9).
As the coolant enters the block,
it travels through cored passages to
cool the entire length of each cyl-
inder wall. Upon reaching the rear
of the cylinder block, the coolant is
directed upward into the cylinder
head where it cools the combustion
chambers, valves, and valve seats on
its return to the front of the engine.
The coolant from the cylinder
head flows past the thermostat if it is
open, into the radiator supply tank. If
the thermostat is closed, a small por-
tion of the coolant is returned to the
water pump for recirculation. The en-
tire system is pressurized to 13-15 psi.
ENGINE REMOVAL AND INSTALLATION
The engine removal and installa-
tion procedures are for the engine
only without the transmission at-
tached. The engine installation is
shown in Fig. 10.
REMOVAL
1. Drain the cooling system and
the crankcase. Remove the hood.
2. Disconnect the battery ground
cable at the battery, the heater hose
at the water pump and coolant outlet
housing, and flexible fuel line at the
fuel tank line.
3. Disconnect the radiator upper
hose at the radiator supply tank. Dis-