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MASSEY.FERGUSON
TECUMSEH EA'G'A'ES
MODEL
H7O
GROUP
O-SECTION
V-PART
8
ll.
Check
cylinder head for cracks, broken cooling
fins,
or
other
damage.
Lay
cylinder head
on a
flat
surface
to
check
for
distortion
or
warping.
Replace
damaged
cylinder
head.
12.
Check
valve
guides
for
scoring and wear.
If
guides are
worn
to
more than standard guide
sizes
listed
in
"Specifications",
valve guides can be
rebored
to
accommodate
a
valve
with a
t
/n-inch
oversized
stem. Refer
to
"Reboring Valve Guides".
NOTE:
Vahse
guides
are
permanentlg
installed
in cglinder and are not replaceable.
13. To
reassemble
engine, proceed
as
follows:
a.
Install
crankshaft, camshaft,
piston and
rod
as-
sembly.
b.
Install cylinder
cover, valves and breather
as-
sembly.
c.
Install
magneto
and cylinder head. Tighten
head
bolts
in the
sequence
illustrated in Fig.
9.
(Tighten
bolts to
torque indicated in "Specifications".
REBORING
THE CYLINDER
If
cylinder
is
more
than
.005
inch larger than standard
bore
size
listed in "specifications,"
it
must
be
rebored
as
follows:
I.
Dismantle engine as described
in
Steps
I
through
5
of
"Cylinder."
2.
Thoroughly clean cylinder
with
solvent.
3.
Determine
if
cylinder should be rebored for
.010
inch or
.02,0
inch
oversize
piston and rings. This is
the
nearest
available size which
will
permit clean-up of
cylinder wear completely.
4. Use any standard commercial hone
of
suitable
size.
Chuck hone
in drill
press
that has
a
spindle
speed
of
approximately
600
rpm.
5. Install set
of
coarse stones
in
hone and
center
cylinder under spindle
of drill
press.
Lower hone
to
point where lower end of
stones
are
in
contact
with
Iowest
point in cylinder
bore.
6.
Rotate
adjusting
nut
so
that
stones
touch
cylinder
wall
and
begin
honing
at
bottom
of
cylinder. Move hone
up and down at rate of 50
strokes
per
minute to avoid
cutting ridges
in
cylinder wall. Every fourth of fifth
stroke,
move hone
far
enough
to
extend
the
stones one
inch beyond
top
and
bottom
ofcylinder
bore.
7.
Check
bore every
thirty or forty
strokes
for
size
and
straightness
to
make certain
that cutting is
pro-
gressing satisfactorily.
If
stones
are collecting
metal,
clean
with
a wire brush
each
time hone is
removed.
B.
Continue honing operation
with
coarse
stones
until cylinder
bore is
within
.002
inch of
desired
finish
size.
Then replace
coarse stones
with
burnishing
stones
and continue
in
same
manner
until
bore is
to
rvithin
.0005
inch of desired
size.
9.
Remove
burnishing
stones
and install
finishing
stones to
polish cylinder to final
size.
10. Clean
cylinder
with
solvent and
dry thoroughly.
Il.
When
reassembling
the
engine (described in
paragraph
13
of "Cylinder"),
replace
piston and piston
rings
with
oversized
parts.
i.
-:_
t':
{
6
F_=_li%
Fis.
9
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