bore dimension and piston and ring clearance
should be correct.
IAWARNINGI
Metalworking techniques can en-
danger eyes
and
hands. Make certain to wear
goggles when performing these procedures.
When reboring cylinders, take these precautions:
1. Make sure the cutting tool is properly ground.
2.
Be sure that the top of the engine block is
smooth and free of deposits.
3.
Clean the base of the boring bar before the bar
is set up. Deposits under the boring bar will
cause
it to tilt, causing the cylinder to be dis-
torted after boring.
4.
Make an initial rough cut, followed by a finish
cut. Then hone the cylinder bore to the speci-
fied oversize.
Honing Cylinders Using Precision Hones
Refer to the hone manufacturer's recommended
grit size
to produce the specified surface finish of 20
to 40 RMS. Too rough a finish will wear out the pis-
ton rings, and too smooth a finish can retard piston
ring seating.
1. Position the block solidly for either vertical
or
horizontal honing. Use either a drill press or a
heavy-duty drili which operates at approxi-
mately 250
to 450 rpm.
2. Follow the hone manufacturer's instructions
for the use of oil or lubricant on the stones. Do
not use lubricants with a dry hone.
3. Insert the hone in the bore, and adjust the
stone to
fit snugly to the narrowest section.
When adjusted correctly, the hone should not
shake
or
chatter
in
the cylinder bore, but will
drag freely up and down when hone is not run-
ning.
4. Connect the drill to the hone and start the drill.
Note that high spots
in
the bore cause an in-
creased drag on the stones. Move the hone up
and down in bore with short overlapping
strokes, about 40 times per minute. Usually
9-20
the bottom of the cylinder must be honed first,
because it is smaller. As the cylinder takes a
uniform diameter, move the hone up and down
through the length of the cylinder bore.
5.
Check the diameter of the cylinder regularly
during honing, at six places in the bore; meas-
ure twice at top, middle, and bottom at 90-de-
gree angles. A dial bore gauge is the easiest
method, but a telescoping gauge can be used.
6. The crosshatch formed by the stones should
form an included angle of 23 degrees. This
can be achieved by moving the rotating hone
(250 to 450 rpm) up and down in the cylinder
bore roughly
40 times per minute.
7. Clean the cylinder bores thoroughly with soap,
water and clean rags.
A clean white rag should
not become soiled on the cylinder wall after
cleaning is complete.
Do not use gasoline
or
other solvents to clean
the cylinder walls. Solvents wash oil from the
walls, but leave metal particles.
8. Dry the crankcase and coat it with oil.
Deglazlng Cylinder Bores
Deglazing the cylinder bore provides cavities to
hold oil during piston ring break-in. Deglazing pro-
duces a good finish, but does not enlarge the cylin-
der diameter, so the original pistons with new rings
may still be used. Deglaze the cylinder bores if
there are no scuff marks and no wear
or
out-of-
round beyond specifications before installing new
rings.
1. Wipe cylinder bores with a clean cloth which
has been soaked in light engine oil.
2.
Use a brush-type deglazing tool with coated
bristle tips to produce a crosshatch pattern
in
the cylinder bore.
3. The degiazing tool should be driven by a slow-
speed drill. Move the deglazing tool up and
down in the cylinder
(1
0 to 12 complete
strokes) rapidly enough to obtain a crosshatch
pattern, as shown in Figure 9-32.
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