Ford COUGAR 1968 Shop Manual page 344

GROUP 8
-
Engine
V A L V E O P E N V A L V E CLOSED
FIG. 8
-
Type 1 Hydraulic Valve Lifter
V ~ L V E OPEN
I
LIFTER BODY-
PUSH ROD CUP
-
FIG. 9-Type I I Hydraulic valve Lifter
lobe. This increases the push rod
force against the lifter plunger and
hydraulic pressure immediately builds
up in the compression chamber until
it acts as a solid member of the valve
operating mechanism. The lifter then
becomes a hydraulic ram which forces
the valve in the cylinder head to open.
During this period, a slight leakage of
oil past the plunger occurs (calibrated
leak down rate).
As the high point of the camshaft
'LINDER
ILOCK
/
L GALLERY
lPPLY
4MBER
VALVE
i N )
lobe rotates and passes by the foot
of the valve lifter, the valve in the
cylinder head seats and the valve
lifter assembly is forced downward.
Reduced force on the lifter plunger
at this time relieves the pressure on
the lifter plunger and it is free to be
moved upward by the plunger spring.
This action allows oil to flow once
again through the oil holes in the
lifter body and plunger.
The operating cycle is completed
for each revolution of the camshaft.
Zero clearance (lash) in the valve
train mechanism is maintained at all
times by the hydraulic force and ex-
pansion of the plunger spring be-
tween the lifter body and plunger.
It should be noted that it is normal
for a hydraulic tappet that is holding
a valve open to leak down during ex-
tended (overnight) shut-down periods.
Such a tappet will be noisy for a few
seconds following start-up.
Oil from the oil pan sump, located
in the front of the oil pan, is forced
through the pressure-type lubrica-
tion system (Fig. 10) by a rotor oil
pump. A spring-loaded relief valve in
the pump limits the maximum pres-
sure of the system. Oil relieved by
the valve is directed back to the in-
take side of the vumv.
All the oil discharged by the pump
passes through a full flow-type Autolite
filter before it enters the engine. The
filter is mounted at the lower left front
of the engine.
On a cartridge-type oil filter, a
relief valve in the filter permits oil
to bypass the filter i f the element
becomes clogged.
On an element-type oil filter, a by-
pass in the center bolt provides oil
to the engine in case the filter ele-
ment becomes clogged. The bypass is
located in the hollow center bolt of
the filter and consists of a spring-
loaded valve. When the element is
clean and oil will flow through it, the
pressure difference between the inner
and outer faces of the valve is not
great enough to overcome the spring
pressure behind the valve. Therefore,
no oil flows through the bypass.
When the element is dirty and will
not permit a sufficient flow of oil,
the pressure acting on the inner face
of the valve drops. If the pressure dif-
ference between the valve faces is great
enough to overcome spring pressure,
the valve will open. Oil then bypasses
the element, maintaining an emer-
gency supply of oil to the engine.
From the filter, the oil flows into
the main oil gallery which is located
to the right side of the camshaft. The
oil gallery supplies oil to each indi-
vidual main bearing, through drilled
passages in the block. Passages are
drilled from each main bearing to
each camshaft bearing. Number 1
main bearing feeds No. I camshaft
bearing, and No. 2 main bearing
feeds No. 2 camshaft bearing, etc.
The oil then flows through notches