A.
B.
C.
Measure and record as
“A”
the
cylinder bore
diameter (parallel to crankshaft) near the top
of
cylinder bore where greatest amount
of
wear occurs.
Also
measure and record as “B”cy1inder bore
diameter (parallel to crankshaft) at the bottom
of
piston travel.
Measure and record as
“C”
cylinder bore
diameter (perpendicular to crankshaft) near
the top
of
cylinder bore where greatest
amount of wear occurs.
TOP END
OF
CY
LlNDER
BOTTOM
OF
RING
TRAVEL
e418
RING
AREA
,WEAR
D.
Also measure and record as
“D”
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”
indicates cylinder taper.
If
cylinder taper exceeds that specified in
DIM-
ENSlONSAND 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
DlMfNSlONS
AND CLEARANCES,
the cylinders must be
rebored and honed to the next oversize.
A
reboring machine is used when going to over-
size pistons.
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 bore should be
resized
to
the smallest standard oversize diameter at
which it will clean up.Thefinalfinishand borediameters
should then be obtained by honing. Final bore diameter
should equal the standard diameter added to the
b
4
oversize.
Improper boring
wi//
resulf
in
engine
k@%!@!l
damage. Boring
musf
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
using
it.
free.
2.
Be
sure
top
of
engine block is smooth and deposit
10.1
1
Redistribution or publication of this document,
by any means, is strictly prohibited.
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