3.
Clean base of boring bar before bar is set up.
Deposits under boring bar will cause
it
to
tilt,
and
the cylinder will be distorted after boring.
4.
Makean initial rough cut, followed byafinish cut.
Then hone cylinder bore to the specified oversize.
Honing Cylinders (Using Precision Hones)
Refer to hone manufacturer’s recommended grit size
to produce specified surface finish
of
20 to
40
RMS.
Too rough
of
a finish will wear out the rings and too
smooth of a finish can retard piston ring seating.
1.
Position block solidly for either vertical or hori-
zontal honing. Use either a drill press or heavy-
duty drill which operates at approximately 250 to
450 rpm.
2. Follow hone manufacturer’s instructions for the
use of oil or lubricant on stones. Do not use lubri-
cants with a dry hone.
3.
Insert hone in boreand adjust stonestofitsnugly
to the narrowest section. When adjusted cor-
rectly, the hone should not shake or chatter in
cylinder bore, but will drag freely up and down
when hone is not running.
4. Connect drill to hone and start drill. Feel out bore
for high spots, which cause an increased drag on
stones. Move hone up and down in bore with
short overlapping strokes about
40
times per
minute. Usually bottom of cylinder must be
worked out first because
it
is smaller.
As
cylinder
takes a uniform diameter, move hone up and
down all the way through cylinder bore.
5.
Check diameter of the cylinder regularly during
honing.
A
dial bore gauge is the easiest method,
but
a
telescoping gauge can be used. Check size
at six places in bore; measure twiceat top, middle
and bottom at SO-degree angles.
6.
Crosshatch formed by the stones should form an
included angle of 23 degrees. This can be
achieved by moving the rotating hone (250 to450
rpm) up and down in cylinder bore about 40 times
per minute.
7.
Clean cylinder bores thoroughly with soap, water,
and clean rags.
A
clean white rag should not
become soiled on wall after cleaning is complete.
Do
not use a solvent or gasoline, since they wash
oil from the walls but leave metal particles.
8.
Dry crankcase and coat
it
with oil.
Deglazing Cylinder Bores
Deglaze the cylinder bores if there are no scuff marks
and no wear or out
of
round beyond specifications
before installing new rings. Deglazing gives a fine
finish but does not enlarge cylinder diameter,
so
the
original pistons with new rings may still be used.
The reason for deglazing a cylinder is to provide
cavities to hold oil during piston ring break-in.
1.
Wipe cylinder bores with a clean cloth which has
been dipped in clean, light engine oil.
6
2.
Use
a brush type deglazing tool with coated bris-
tle tips to produce a crosshatch pattern in the
cylinder bore.
3. The deglazing tool should be driven by a slow
speed drill. Move deglazing tool up and down in
cylinder
(10
to
12 complete strokes) rapidly
enough to obtain a crosshatch pattern as shown
in Figure
70.
PRODUCE
CROSS
HATCH
SCRATCHES
FOR
FAST
RING
SEATING
AVOIDTHIS
FINISH
01091
FIGURE
70.
CROSS
HATCHING
Never use gasoline or commer-
cial cleaners to clean cylinder
bores after deglazing
or
honing. These solvents
will not remove abrasives from
the
walls.
Abra-
sives not removed from engine will rapidly wear
rings, cylinder walls, and bearing surfaces of all
lubricated
parts,
4. Clean cylinder bore thoroughly with soap, water,
and clean rags. Continue cleaning until a clean
white rag shows no discoloring when wiped
through cylinder bore.
50
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