2.
Record measurements taken at top and bottom of
piston
travel
as
follows:
TOP
END
OF
CYLINDER
A.
Measure and record as
“A”
the cylinder bore
diameter (parallel to crankshaft) near the
top
of
cylinder bore.
6.
Measure and record
as
“B”
cylinder bore
diameter (parallel to crankshaft) at the bottom of
piston travel.
C.
Measure and record as
“Cy’
cylinder bore
diameter (perpendicular to crankshaft) near the
top
of
cylinder bore.
D.
Measure and record as
’ID”
cylinder bore
diameter (perpendicular to crankshaft) at the
bottom of piston travel.
E.
Reading
“A’
subtracted from reading
“B
and
reading
“C”
subtracted from reading
“D”
indi-
BOTTOM
OF
RING
TRAVEL
8410
cates cylinder taper.
If
cylinder taper exceeds that specified in
DIMENSIONS AND CLEARANCES
rebore and
hone cylinder to the next oversize.
F.
Reading
“A”
compared to reading
“C”
and
reading
“B’
compared to reading
“D”
indicate
whether or not cylinder is out
of
round. If out of
round exceeds that specified in
DIMENSIONS
AND CLEARANCES
the cylinders must be
rebored and honed to the next oversize.
FIGURE
18.
METHODS OF MEASURING
THE
DIAMETER
OF
A
CYLINDER
BORE
Reboring
the
Cylinder
Rebore and hone engine whenever cylinder bore is
worn, damaged, out of round, or if cylinder taper
exceeds specifications.
A
worn cylinder boreshould be
resized to the smallest standard oversize diameter at
which it will clean up. The final finish and borediameters
should then be obtained by honing. Final bore diameter
should equal the standard diameter added to the
oversize.
Improper boring will result in engine
damage. Boring must be done
by
qualified mechanics.
After boring to the correct oversize cylinder bore
dimension piston and ring clearance should be
appropriate. There is no need to adjust or “fit” pistons
and rings.
When reboring cylinders, take the following pre-
cautions:
1.
Make sure cutting tool is properly ground before
2.
Be sure top of engine block is smooth and deposit
using it.
free.
10-1
1
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