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20
Engine
Tractors,
Lawn
and
Garden
-
110
and
112
30-6
Cylinder
Head
and
Valves
-
Tecumseh
SM
-2059-(Apr-67)
INSPECTING
VALVES-Continued
Th
e
valv
,
-,
s e.lt
an
g
le"
B"
depend
s
upon
val
v
face
an
g
le
"C."
Nf
~
W
valves
ha
ve
a 45°fa
cc.
R
e-
fac
e
or
stem.
Replace
valves
with
warped
head.
condition
valve
seats
with
46
"
cutters
and
lap
Recondition
or
replace
valv
es
with
less
than
valv
e
s.
See
pagl'
30-7.
1/
64-inch
margin.
Valve
stem
ends
should
be
ground
square
before
checking
valve
tappet
clearance.
/
o
RECONDITTON1NG OR
REPLACING
VALVES
A
Val
ue
Guides
Clean
the
valve
guides
first
to
aSSur
e
valve
alignment
when
cutting
valve
seats.
(ig
.
14-Mea
s
uri"g
Valve
Guide
Fig
.
15-Measuring
Valve
Slem
Use
valve
guide
cleaner
to
clean
inside
of
valve
gui.de.
Then
measure
T.D. of
valve
guide,
Figure
14,
and
O.D.
of
valve
stem,
Figure
15.
Refer
to
"Specifications,"
page
30-11,
for
toler-
ances.
Ream
guides
as
ne
cessa;y.
Vall'e
Seats
A
broken
or
worn
exhaust
valve
seat
(insert)
may
be
replaced.
See
page
30-8.
They
are
either
stellite
or
molychrome
nickel.
Th
e
intake
valve
s e
at
is
machined
into
the
cylind
er
block.
Th
e
valve
seating,
surface
"A,
II
Figure
16,
should
be
held
as
close
to
3/ 64
inch
as
possible.
Scats
with
more
than
1/
16-inch
seating
surface
should
be
narrowed
(cut
back)
with
a 31
0
cutter,
!fE,
T'
Figure
16.
M 61 S8
A.
Valve
Seot
i
ng
Suriac"
(3 '
64·inch)
B.
Valve
Scot
Angl
e
(46<>j
C
Val
ve
Face
An
gle
(
45°)
D.
Valve
Margin
(1
/
16
·
inch)
E.
Valve
Harrowing
Angle
(31°)
Fig.
16-Vafve
Seal
and
Surfa
ce
Dimension
S
.1':l \ ( SLAT
'.L
TT,
R
M '56"
F
ig
.
17-Vafve
Seal
Culler
This
valve
seat
cutter
will
cut
a
46°
valve
seat
and
narrow
the
seat
to
31°.
See
"Special
Tools,"
pag
e
30-12,
for
tool
number
and
manu-
facturer.
When
rec
o
nditioning
valv
es
.
be
sure
there
is
no
more
than
1/
16-inch
and
no
less
than
1/
64-
inch
margin
liD"
on
the
valve.
Litho
in
U.
S.
A.