Pontiac Fiero 1988 Service Manual page 299

6A-22 GENERAL ENGINE MECHANICAL
© If the bore is glazed, but otherwise
serviceable, break the glaze lightly with a
hone and replace the piston rings.
• Make sure the honing stones are clean,
sharp and straight. Move the hone slowly
up and down to produce a 45° cross-hatch
pattern. Clean bore thoroughly with soap
and water. Dry and rub-in clean engine oil,
remeasure.
Figure 49 Measuring Cylinder Bore For Taper and Out of
Round
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G2004
M
6-6A
Figure 50 Cylinder Wear Pattern
Assemble
Cooling jacket plugs. Apply GM 1050026 sealer,
Fel Pro-Set and Seal, or equivalent.
Oil gallery screw plug
? 1 Important
• Make sure plugs with oil holes are
reinstalled in their original position to
provide lubrication to the timing chain and
to the distributor. Refer to Specific Engine
Section.
• Camshaft bearings (refer to Camshaft and
Camshaft Bearings)
PISTON FITTING
Important
When fitting pistons, both piston and
cylinder bore condition must be considered
together. Production and service pistons
have the same nominal weight and can be
i.
intermixed without affecting engine
balance. If necessary, used pistons may be
fitted selectively to any cylinder of the
engine, if they are in good condition.
% Do not cut oversized pistons down, or
engine balance will be affected.
Measure
Piston. If worn or damaged, replace with a
standard or oversized piston.
Cylinder bore (Figure 51), refer to Cylinder
Block. If worn beyond specifications, rebore and
hone to size.
GAGING POINTS
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BORE GAGING POINTS
G20047 6A
Figure 51 Cylinder Bore Gaging Point
Important
• Finish hone when selecting piston.
Fit piston to cylinder.
Important
• Both piston and cylinder bore must be dry.
Clean
Scrub the cylinder bore and the piston with soap
and water and remove all foreign material. Dry
and rub-in clean engine oil.
Measure
Check piston to cylinder bore clearance as
follows:
a. Measure the cylinder bore diameter with a
telescopic gage.
b. Measure the cylinder bore diameter. When
measuring piston for " size or taper,
measurement must be made as shown in
Figure 52.
c. Subtract piston diameter from cylinder bore
diameter to determine piston to bore
clearance.
d. Compare piston to bore clearance obtained
with that specified.