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THE
ENGINE
A
facilitate this an
old
piston ring can be
sprung
into the
bore
so
that
it
rests on
top
of the piston.
The
cylinder
head is next given attention. The
sparking
plugs
must be
re.
m oved, olcaned, and adjusted. Clean off
the carbon deposit
from
the valve
stems,
valve ports, and
combustion
spaces
of the
cylinder
bead.
Remove
all
traces
of carbon dust with compressed
air
or by the
vigorous
usc of
a
tyre pump
and
t
hen
thoroughly
clean
with paraffin (kerosene) and
dry
off.
Fit a new
cylinder
bead gasket.
Section
A.lS
VALVES
Re-ral
Remove
the
cylinder
bead
(Seetion A.
13)
and
remove
the camshafts
(Seetion A.
II).
Withdraw the tappets with
a
valve grinding
suction
tool and remove tht tappet
adjusting
shims (see
Fig.
A.S).
Keep
the tappets, adjusting shims, and valves in
their
relative
positions to
ensure replacement in
their
original locations.
Compress the
valve
springs
with a
suitable compressor
and remove
the
two valve
retainers. Release
the valve
springs and remove the
compressor,
the valve spring cup,
the
inner and
outer valve
springs, and the
valve spring
thrust washer.
Withdraw
the valve from the guide.
R.mu.a
To
replace
the
vah-es place
each
val,·e
in
its guide
and
replace the thrust washer, the valve springs, and
the
valve spring cup.
Compress
the
valve
springs
with
the compressor and
refit the
valve
spring retainers.
Remove
the
compressor
and
refit
the tappet adjustment shim and the tappel.
The
valve clearances
should
be checked and adjusted after
final assembly (see Seetion
A.
I
8).
Section
A.l6
VALVE GUIDES
Raaoftl
Disconnect
the camsbafl driving sprockets and remove
the cylinder head as detailed in Seetion
A.IJ.
Remo.,.e
the
appropriate
camshaft.
, valve,
and springs as
in Section
A.l5.
The
valve guides are
shouldered
and can therefore
only
be
removed
by driving through from
the
combustion
chambers.
Rest
the camshaft cover joint face of
the
cylinder
head
on
a
smooth wooden block
of sufficient
thickness
MOA
(Twin Cam).
l15ue
2. 23026.
Fig.
A
.4
The ct1111$hoft
housing
(~utioMtl)
positiont!d
on a
M'OOden
bloek for Yofl·e guidl! rl!mO>-al
to keep the
camshaft
bearing cap
studs
clear of the
press
table
(see
Fig.
A.4)
and drive the
valve guide
through
from the
combustion chamber wnh
a suitably
siud
drifL
This
should take
the
form of a hardened-steel
punch
-&in. (14
mm_) in
diameter and not
less
than
4
in.
(IOcm.)
in length,
with a locating spigot
it
in.
(8
mm.) diameter
machined on one end for a
length
of
I
in. (2·5
em.)
to
engage the bore of
the
guide.
Replacement
When
nuing new valve guides they
should be
pressed in
from
the top
of the cylinder head
until the
flange registers
on the bottom
of
the
valve spring
recess.
Section A.l
7
VALVES A:-.10
SEATINGS
GrindiDg
and
testing
Remove
the valves as
in
Section A.l5.
Each valve must be cleaned thoroughly and carefully
examined
for pitting.
Valves in a pitted
condition
should
A.1
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