Specifications

1-4
GROUP 1-ENGINES AND EXHAUST SYSTEMS
ENGINE TROUBLE DIAGNOSIS
ENGINE RUNS, BUT
MISSES (Continued)
ROUGH ENGINE IDLE
GUIDE (Continued)
If a good spark occurs, check the
spark plug. If the spark plug is not
at fault, a mechanical component
of the engine is probably at fault.
ENGINE
Perform a compression test to de-
termine which mechanical compo-
nent of the engine is at fault.
MISSES ERRATICALLY
AT ALL SPEEDS
EXHAUST SYSTEM
Exhaust system restricted.
IGNITION SYSTEM
Defective breaker points, con-
denser, secondary wiring, coil, or
spark plugs.
High tension leakage across the
coil, rotor, or distributor cap.
FUEL SYSTEM
Float setting incorrect.
Fuel inlet system not operating
properly.
Dirt or water in the fuel lines or
carburetor.
Restricted fuel filter.
COOLING SYSTEM
Check the cooling system for in-
ternal leakage and/or for a condi-
tion that prevents the engine from
FUEL SYSTEM
Engine idle speed set too low.
Idle fuel mixture needle(s) not
properly adjusted.
Float setting incorrect.
Air leaks between the carburetor,
spacer, and the manifold and/or
fittings.
Fuel leakage at the carburetor
fuel bowl(s).
Power valve leaking fuel.
Idle fuel system air bleeds or fuel
passages restricted.
Fuel bleeding from the accelerat-
ing pump discharge nozzle(s).
Secondary throttle plate(s) not
closing (4-barrel carburetor).
Improper secondary throttle plate
stop adjustment (4 - barrel car-
buretor).
Incorrect idle speed setting of the
secondary carburetors (390 Super
High Performance V-8).
Leaking fuel pump, lines, or fit-
tings.
reaching normal operating tempera-
ture.
ENGINE
Perform a compression test to de-
termine which mechanical compo-
nent of the engine is at fault.
MISSES AT IDLE ONLY
FUEL SYSTEM
Idle fuel mixture needle(s) not
properly adjusted.
IGNITION SYSTEM
Excessive play in the distributor
shaft.
Worn distributor cam.
ENGINE
Perform a compression test to de-
termine which mechanical compo-
nent of the engine is at fault.
MISSES AT HIGH SPEED
ONLY
FUEL SYSTEM
Power valve clogged or damaged.
Low or erratic fuel pump pres-
sure.
Fuel inlet system not operating
properly.
Restricted fuel filter.
COOLING SYSTEM
Engine overheating.
IGNITION SYSTEM
Improperly adjusted or defective
breaker points.
Fouled or improperly adjusted
spark plugs.
Incorrect ignition timing.
Spark plug misfiring.
EXHAUST SYSTEM
Exhaust gas control valve inop-
erative or sticking.
ENGINE
Loose engine mounting bolts or
worn insulator.
Cylinder head bolts not properly
torqued.
Valve lash set too tight (engines
with mechanical valve lifters).
Crankcase ventilation regulator
valve defective or a restricted tube
(Positive Crankcase Ventilation Sys-
tem).
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