Flywheel - Chevrolet 1980 Light Duty Truck Service Manual

6A 1-28 IN-LINE 6
then .005" wear or taper may not entirely clean up when
fitted to a high limit piston. If it is desired to entirely clean
up the bore in these cases, it will be necessary to rebore for
an oversize piston. If more than .005" taper or wear, they
should be bored and honed to the smallest oversize that will
permit complete resurfacing of all cylinders.
When pistons are being fitted and honing is not
necessary, cylinder bores may be cleaned with a hot water
and detergent wash. After cleaning, the cylinder bores
should be swabbed several times with light engine oil and
a clean cloth and then wiped with a clean dry cloth.
Boring
1. Before using any type boring bar, the top of the
cylinder block should be filed to remove any dirt or burrs.
This is very important. If not checked, the boring bar may
be tilted which would result in the rebored cylinder wall not
being at right angles to the crankshaft.
2. The piston to be fitted should be measured with a
micrometer, measuring at the center of the piston skirt and
at right angles to the piston pin. The cylinder should be
bored to the same diameter as the piston and honed to give
the specified clearance.
3. The instructions furnished by the manufacturer of
the equipment being used should be carefully followed.
Honing
1. When cylinders are to be honed follow the hone
manufacturer's recommendations for the use of the hone
and cleaning and lubrication during honing.
2. Occasionally during the honing operation, the
cylinder bore should be thoroughly cleaned and the piston
selected for the individual cylinder checked for correct fit.
3. When finish honing a cylinder bore to fit a piston,
the hone should be moved up and down at a sufficient speed
to obtain very fine uniform surface finish marks in a cross-
hatch pattern of approximately 45 to 65° included angle.
The finish marks should be clean but not sharp, free from
imbedded particles and torn or folded metal.
4. Permanently mark the piston for the cylinder to
which it has been fitted and proceed to hone cylinders and
fit the remaining pistons.
Handle the pistons with care and do not
NOTICE:
attempt to force them through the cylinder until the
cylinder has been honed to correct size as this type
piston can be distorted through careless handling.
5. Thoroughly clean the bores with hot water and
detergent. Scrub well with a stiff bristle brush and rinse
thoroughly with hot water. It is extremely essential that a
good cleaning operation be performed. If any of the abrasive
material is allowed to remain in the cylinder bores, it will
rapidly wear the new rings and cylinder bores in addition
to the bearings lubricated by the contaminated oil. The
bores should be swabbed several times with light engine oil
and a clean cloth and then wiped with a clean dry cloth.
Cylinders should not be cleaned with kerosene or gasoline.
Clean the remainder of the cylinder block to remove the
excess material spread during the honing operation.
PISTON SELECTION
1. Check USED piston to cylinder bore clearance as
follows:
a. Measure the "Cylinder Bore Diameter" with a
telescope gage (2-1/2" (64mm) from top of cylinder bore).
b. Measure the "Piston Diameter" (at skirt across
center line of piston pin).
c. Subtract piston diameter from cylinder bore
diameter to determine "Piston to Bore Clearance".
d. Determine if piston to bore clearance is in the
acceptable range.
2. If used piston is not acceptable, determine if a new
piston can be fitted to the cylinder bore.
3. If cylinder bore must be reconditioned, measure
new piston diameter (across center line of piston pin) then
hone cylinder bore to correct clearance.
4. Mark the piston to identify the cylinder for which
it was fitted.

FLYWHEEL

Removal
All Except L25 Engines
1. Remove transmission and/or clutch housing and
clutch from engine.
2. Remove flywheel retaining bolts and remove
flywheel.
L25 Engines
1. Remove transmission and/or clutch housing and
clutch from engine.
2. Mark relationship of flywheel and crankshaft so
that dowel holes can be aligned in their original positions
on assembly.
3. Remove engine oil pan and rear main bearing cap.
4. Remove flywheel
crankshaft dowels out of flywheel and crankshaft. Rotate
crankshaft as necessary so dowels clear cylinder block.
5. Remove flywheel and discard used dowel pins.
Repair
Only repair recommended at flywheel used with
conventional clutch is replacement of starter gear in event
gear is worn or otherwise damaged.
Use torch to heat the gear around entire circumference,
then drive the gear off flywheel, using care not to damage
the flywheel.
Uniformly heat the flywheel gear to temperature which
will expand gear to permit installation. [Temperature must
not exceed 400°F (204° C)].
As soon as gear has been heated, install on flywheel.
NOTICE: NEVER HEAT STARTER GEAR TO
RED HEAT AS THIS W ILL CHANGE METAL
S T R U C T U R E .
Installation
A ll Except L25 Engines
1. Clean the mating surfaces of flywheel and
crankshaft to make certain there are no burrs.
2. Install flywheel on crankshaft and position to align
dowel hole of crankshaft flange and flywheel.
retaining bolts and drive
LIG H T T R U C K S ER V IC E M AN UAL