Datsun 1980 200SX Service Manual page 56

CYLINDER HEAD
CYLINDER
HEAD
MATING
FACE
I Make
a
visual check for cracks and
flaws
2
Measure the surface of cylinder
head
on
cylinder
block side for
warpage
If
beyond
the
specified
limit
correct
with
a
surface
grinder
Warpage
of surface
limit 0 1
mm
0 004
int
It Cil
SEM14g
Surface grinding
li it
The grinding
limit of
cylinder
head
is
determined by
the
cylinder
block
grinding
in
an
engine
Depth
of cylinder head
grinding
is
A
Depth
of
cylinder
block
grinding is
8
limit
A B 0 2
mm
10 008
in
VALVE GUIDE
Measure the clearance between
valve
guide
and valve
stem
If the
clearance exceeds the
specified
limit
replace the
worn parts or
both valve
and valve guide
In
this
case
it is
essential
to detennine
if such
a
clear
ance
has been caused by
a worn Or
bent valve
stem
or
by
a
worn
valve
guide
Determining clearance
Precise method
I Measure the diameter of valve
ENGINE MECHANICAL
lnspectionandRepair
INSPECTION AND REPAIR
stem
with
a
micrometer in three
places top
center and bottom
2 Measure valve
guide
hore
at center
using telescope
hole
gauge
F
A
T
Mr
h
oP
10
1
L
j1
@
I
C
d
SEM150
3
Subtract the highest reading of
valve
stem
diameter from valve
guide
bore
to
obtain the
stem
to
guide clear
ance
Stem
to guide
clearance
limit 0 1
mm
10
004 in
2
Expedient
method
Pry
valve in
lateral
direction
and
measure
deflection
at stem
end with
dial
gauge
Stem end deflection
limit 0 2
mm
0 008 in
Valve
should be moved in
parallel
with
rocker
arm
Generally
a
large
amount
of
wear occurs
in this
direC
tion
SEM151
Replacement
of valve
guide
1
To
remove old guides
use
Tool
S111033000 and
a
press
under
a
2 ton pressure
or
a
hammer
Drive them
out
toward rocker
cover
Heated cylinder
head will
facilitate the
operation
2 Ream cylinder head valve
guide
hole
using
Tool at room
temperature
Reaming
bore
12
185 12 196
mm
0 4797 0 4802 in
SEM152
3 Fit snap
ring
on new
valve guide
and press the
guide into
head until
snap
ring comes
in
contact
with
cylinder head surface after
heating
cylinder head
to 150 to
2000C
302 to
3920F
Valve
guide
of 0 2
mm
0
008
in
oversize diameter is available for
service Refer
to
S D S
4 Ream
the
bore
using
1001
STl1032000
Reaming
bore
8 000 8 0 18
mm
0
3150
0
3157
in
5 Correct valve
seat
sur ace
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 Tool
and grind
with
a
grinding
compound
EM