ENGINE
B
The valve springs should
be
Inspected for cracks and
fatigue,
the
latter
being
determined
by
the
spring
length. which should be checked against
that
given
In
the
General·Oata, page GD3.
If
the
spring has
settled by
more
than nIn. It mUst be replaced.
All
parts should be
thoroughly
cleaned
In
kerosene
(paraffin) and allowed
to
drain before reassem-
bling.
• Assemble
the
Inner and
outer
springs and top and
bottom
cups
over
the
valve gUide,
then
slide
the
valve Into position having first lubricated
the
~tem
with a small
amount
of
graphlted
all.
Compress
the
springs with
the
Service
tool
and
slide
the
split cotters Into
the
exposed
groove
In
the
valve stem.
When
the
assembly
Is
completed It
Is
advisable to
tap the end of each valve stem
with
a hide
faced
mallet
to
ensure
that
the
cotters
are
fitted securely.
• Each
outer
spring
has
a
closed
coil
(i.e.
reduced
pitch)
at
one
end.
This
end
carries
the
colour
code
identification,
and
must
be
fitted
towards
the
cylinder
head.
SECTION
814
RENEWING
THE
VALVE GUIDES
The valve gUides can be
extracted
using service
tool 61-6063
as
shown
In
the
Illustration B16.
The same method may
be
employed
to
fit
the
new
gUide,
except
that
the
replacement
portion
of
the
tool
Is
used,
to
avoid causing damage
to
the
knife
edge
of
the
guide.
When
re-assembllng, lightly grease
the
valve guide
and
ensure
that
the
gUide
Is
pressed
In
until
the
shoulder
Is
flush with
the
cylinder head.
When
new gUides have
been
fitted It
Is
necessary
to re-cut
the
valve seats
In
the
cylinder head and
grind
In
the
valves (section B16).
Fig.
816.
Using
assembly
tool
to
replace
valve
guide
SECTION 815
DECARBONISIN G
Decarbonlslng Involves
the
removal
of
carbon
deposits from
the
piston crowns, combustion
chambers, ports, valve heads, etc.
The presence
of
carbon, which
Is
pne
of
the
products
of combustion,
Is
not
harmful
to
the
engine
pro·
vldlng
that
It
Is
removed
.before
the
~eposlts
become excessive and
therefore
likely
to
cause
pre-Ignition
or
other
faults which may Impair
performance.
The usual symptoms, Indicating
the
need for
decarbonlslng are, a tendency
to
"pink"
(metallic
knocking sound when
under
load), a general failing
B19
To Next Page
Loading...
