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Section 2-Engine Tune-Up
9
which cannot be cleaned up by a light application of
the point file.
(5) CHECK ENCINE VACUUM AND ADJUST
CARBURETOR
IDl~E.
Check the engine manifold
vacuum at idle speed.
If
the vacuum is lower than normal, check for leak-
age at the vacuum lines and intake manifold. Check the
carburetor idle adjustment.
If the vacuum is still below normal or is erratic, it
is an indication of bad rings, sticky valves, weak valve
springs or leaky gaskets. If this condition exists, it
should be reported to the customer.
Set the carburetor idle speed to specifications. Set
the idle fuel adjustment to the point of highest and
steadiest manifold vacuum and/or at the smoothest en-
gine idle. Reset the idle speed if required.
(6)
CHECK GOVERNOR OPERATION -
256,
279, 317
CUBIC INCH ENGINE. Connect a tachom-
eter to the engine. Start the engine and gradually in-
crease the throttle opening, observing the tachometer
reading, until the no-load cut-off speed is reached. If
the cut-off is not within the specified range, stop the
engine and make the necessary adjustments. Repeat
the test until
th~
correct cut-off speed is obtained.
(7) CLEAN AIR CLEANER AND f'UEL PUMP
BOWL. Clean the air cleaner, and oil the element (dry-
type). If the air cleaner is the oil bath-type, refill to the
indicated level with engine oil of the specified viscosity.
Remove and clean the fuel pump bowl. Install a new
filter in the 223, 239, and 256 cubic inch engines. Clean
the filter in the 279 and 317 cubic inch engines. Install
the sediment bowl and a new gasket.
h. Major Tune-Up.
A major tune-up consists of the following operations:
(1) CLEAN AND INSPECT BATTERY CABLES.
Remove the cables from the battery. Clean the battery
terminals and cable connectors. Inspect the battery case
for cracks and leaks. Fill the battery to the proper
water
level.
Replace deteriorated
connectors, and
cables that are shorted or have worn insulation. Brush
the cable connectors with grease to retard corrosion.
Connect the cables to the battery.
(2) TEST CHARGING SYSTEM. Test the battery
and recharge or replace if necessary to insure depend-
able service. Check the generator output and the regu-
lator. Repair or replace a faulty generator. Adjust or
replace the regulator if necessary.
(3) TEST CYLINDER COMPRESSION. Follow
the procedure under "a. Minor Tune-Up".
(4) CHECK CYLINDER HEAD AND MANIFOLD
BOLT TORQUE. Check the head bolts to the higher
specified torque (cold).
If
the bolt does not move at
this torque, do not tighten further.
If
the bolt torque is
not lower than 20 foot-pounds of the lower specified
limit, tighten the bolt to the higher specified limit. If
the bolt torque is more than 20 foot-pounds below the
lower specified limit, replace the head gasket. Tighten
the intake and exhaust manifold bolts and nuts to 23-28
foot-pounds torque.
(5)
CLEAN,
ADJUST,
AND INSTALL SPARK
PLUGS. Sandblast the spark plugs, wipe the porcelain
clean, file the electrode tips flat, and adjust the spark
gap. Test the plugs in an approved spark plug tester.
Replace any plugs that have broken or chipped porce-
lain, badly burned electrodes, or that do not check satis-
factorily on the tester. Install the spark plugs and
tighten them to the specified torque.
(6) TEST DISTRIBUTOR. Test the distributor
vacuum advance on a suitable distributor test stand,
and make adjustments, repairs, or replacements as re-
quired. Set the distributor point dwell to specifications.
Apply a light coat of distributor cam grease to the cam.
(7)
CLEAN AND INSPECT THE DISTRIBUTOR
CAP. Inspect the distributor cap for cracks or other
damage. Terminal housing sockets should be free from
corrosion.
(8) TIME IGNITION. Before connecting the vac-
uum line between the distributor and carburetor, start
the engine and operate it at idle speed. Check the tim-
ing with a timing light and make the necessary adjust-
ments. Connect the distributor vacuum line after com-
pleting the adjustment and check ignition advance as
the engine is accelerated.
(9) CHECK
IGNITION
PRIMARY
CIRCUIT.
Check the primary circuit amperage with a suitable test
machine. The amperage draw with the engine stopped
should be 5.0 to 5.5 amps. With the engine operating at
idle speed, the amperage draw should be 2.75 to 3.0
amps. Inspect the wires visually for faulty insulation
and poor connections.
(10) TEST SPARK INTENSITY. Determine if the
spark from each spark plug wire will jump a 3/16-inch
gap.
If the spark is unsatisfactory at all spark plugs, trou-
ble exists in the coil, condenser, secondary wiring, rotor
or cap, internally in the distributor, or in the external
primary circuit.
If the spark is unsatisfactory at some but not all of
the spark plug wires, the trouble is in the wire itself,
the wire is not seated in the housing socket, or the dis-
tributor cap is shorted.
(11)
CHECK AND ADJUST VALVE LASH. Check
and adjust the valve lash after the engine is thoroughly
warmed up.
(12) TEST FUEIJ PUMP PRESSURE AND CA-
PACITY. Check the fuel pump pressure. The pressure
should be within 4 to 5 p.s.i. at 900 r.p.m. for the 223,
239, and 256 cubic inch engines and 3.5 to 4.5 p.s.i.
at 900 r.p.m. for the 279 and 317 cubic inch engines.
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