Datsun C210 series - Page 40

Determining
clearance
Precise measurement
of clearance
between valve stem and
valve
guide
needs the aid
of a micrometer
and a
telescope
hole
gauge
By using
these
gauges
check the diameter of
valve
stem
in
three
places top
center
and
bottom
EM030
Fig
EM 25 hecking
Valve Stem
Diameter
Insert
telescope
hole
gauge
in valve
guide
bore
measurlng
at center
Fig
EM 26
Subtract
the highest reading
of
valve
stem
diameter from
valve
guide
bore to obtain the
stem
to
guide
clearance
As an
expedient
a
valve is
pushed
in valve
guide
and
moved to the
right
and
left If its
tip
deflects
beyond
the
specified
limit
there
it
will be
known
that the clearance
between stem and
guide
exceeds the maximum limit
Max allowable deflection
0
2
mm
0
008
in
Max tolerance
Stem to
guide
clearance
0 1 mm 0 004 in
Engine
Mechanical
Note Valve
should he
moved
in
parallel
with rocker arm
General
ly
a
large
amount of wear
occurs in
this
direction
EM115
Fig
EM 27 Measuring
Clearance
between Value Stem
and Value Guide
Replacement
of
valve guide
1 To remove old
guides
use Drift
STII033000
and a
press
under
a
2 too
pressure
or a hammer
Drive
them out from combustion
chamber
side
toward
rocker
cover
Heared
cylinder
head
will
facilitate rhe
operation
2 Ream
cylinder
head valve
guide
hole
using
Reamer
STl1081000
12 2
mm 0 480 in dia at room
tempera
ture
3
Press new
valve
guide
into
head
carefully
so rhat it
will
fit
smoothly
after
heating cylinder
head to 150 to
2000C 302
to
3920
F
Valve
guide
of
0 2
mm 0
008 in
oversize
diameter
is available
for
serv
ice Refer
to Service
Data
and
Specifi
cations
Fig
EM
28
EM 9
4 Ream the bore with
valve
guide
pressed
in
using
Valve
Guide
Reamer
STl1032000
8 0
mm
0 31 in dia
Reaming
bore
8 000 to 8
018
mm
0 3150 t
0 3157 in
5 Correct
valve seat surface
with
new valve
guide
as
the axis
VALVE
SEAT INSERTS
Check valve seat inserts for
any
evidence
of
pitting
at
valve
contact
surface
and
reseat or
replace
if worn
out
excessively
Correct valve
seat
surface
with
Valve Seat Culler STll650001 and
grind
with a
grinding compound
Valve seat insert of 05
mm 0 020
in oversize
is
available
for service
Refer
to Service Data and
Specifica
tions
STJ
165000J
EM299
Fig
EM 29
Correcting
Valve Seat
Replacement
valve seat
In
ert
I Old
insert
can
be removed
by
boring
out
until
it
collapses
The
machine
depth stop
should
be
set so
that
boring
cannot
continue
beyond
the
bottom face of
the insert recess
in
cylinder
head
2
Select
a
suitable
valve seat
insert
and check its outside
diameter
3 Machine
cylinder
head recess
to
the
concentric circles to
valve
guide
center so
that
insert
will have the
correct
fit
4 Ream the
cylinder
head recess
at
room
temperature