Pontiac firebird 1968 - Honing or Boring

SIX CYLINDER ENGINE 6-29
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Fig. 6-56 Measuring Out of Round Taper
Take several measurements parallel and at right
angles to the crankshaft, between 1/2" and 4" from
the top of the cylinder. Subtract the smallest meas-
urement found from the largest. If this figure ex-
ceeds .0006", a piston cannot be fitted properly, and
the cylinder must be honed. New rings and a new
oversized piston must then be fitted.
Fig. 6-58 Measuring Cylinder Gauge
Crankshaft bearings and other internal parts must be
covered or taped to protect them during boring or
honing operation. When taking final cut with a boring
bar, leave ,001" on the diameter for finish honing
to give required piston to cylinder clearance speci-
fications.
Fine vertical scratches made by ring ends will not
cause excessive oil consumption, therefore, honing
to remove is unnecessary.
HONING OR BORING
If a piston in excess
of
honed, to effect a true bore.
.005" oversize is to be
bored, rather than
To eliminate the possibility of honing taper into the
cylinder, full strokes of the hone should be made in
addition to checking measurement at top, middle and
bottom of bore repeatedly.
When boring, always be sure crankshaft is out of
way of boring cutter when boring each cylinder.
NOTE: Honing or boring operation must be done
under close supervision so that specified clearance
between pistons, rings, and cylinder bores is
maintained.
By measuring the piston to be installed at sizing
points (Fig. 6-59) and adding the means of clearance
specification, the finish hone cylinder measurement
can be determined. It is important that both block
and piston be measured at normal room temperature,
60°-90°F.
After final honing and before piston is checked for
fit, each cylinder bore must be thoroughly cleaned.
Use soapy water solution and wipe dry to remove
Fig. 6-57 Normal Cylinder Wear Pattern
Fig. 6-59 Piston Spring Points