Table of Contents
Advertisement
1·4
GROUP 1 - ENGINES AND EXHAUST SYSTEM
A
1357-8
FIG.
6-Vent Tube·Type Crank(ase Ventilation System-
Typi(al
FIG.
7-Positive Crank(ase Ventilation System-
Typi(al
pors
are
discharged to the
atmos-
phere. In the positive
system,
the
crankcase
vapors
are returned to the
intake manifold.
VENT TUBE-TYPE CRANKCASE
VENTILATION SYSTEM
A
crankcase venti lation
tube is
located at
the left front
of
the
engine.
The forward motion of the
car causes
a partial vacuum to be formed
at
the
tube
outlet. This vacuum
act
ion
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
a
ir
from the breather cap
flows
into
the front
section
of the
valve rocker
arm
shaft
chamber.
Here the air normalizes its tempera-
ture
before
contacting
contaminating
vapors originating in the
crankcase.
Warm ventilating air minimizes
the
formation of crankcase sludge.
The ventilating air moves down
past the push rods and into the crank-
case.
Air is diverted from lhe 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 ventilation 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
a ir
being discharged to the atmos-
phere,
it is returned to the intake
manifold. The
air
is returned
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
assembly in-
stalled
in the
carburetor spacer (Fig.
7).
The
valve
regulates the
amount
of
air
to meet
changing operating con-
ditions.
During
idle,
intake
manifold
vac-
uum
is
high. The high vacuum over-
TO
INTAKE
MANifOLD
comes the
tension
of the
spring
pressure and seats
the valve (Fig.
8).
With the
va lve
in this position, all the
ventilating
air
passes through a caJi-
brated
orifice in the valve. With the
va lve seated
there is minimum ven-
tilation. 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 bot-
tom
of the radiator by the water
pump which
delivers the
coolant
to
the cylinder block (Fig. 9).
fROM
CRANKCASE
OUTlET
lOW INTAKE
MANifOLD VACUUM
HIGH SPEED OPERATIONS
TO
INTAKE
MANifOLD
HIGH INTAKE
MANifOLD VACUUM
LOW SPEED OPERATIONS
FIG.
8-Positive Crank(ase Ventilation Regulator Valve
fROM
CRANKCASE
OUTlET
A1458-B
Hide quick links:
Advertisement
Table of Contents
