Cadillac 60 Series 1963 Shop Manual page 236

FUEL AND EXHAUST
10-1
GENERAL DESCRIPTION
The 1963 Cadillac fuel system incorporates a
new positive crankcase ventilating system, de-
signed to reduce the engine's air contaminating
hydrocarbon emissions into the air by burning
much of these fumes. The critical point of the
system is the positive crankcase ventilator valve,
located at the carburetor insulator fitting, Fig.
10-1. This valve controls the flow of fumes en-
tering the engine for burning, and should be
serviced at each oil change.
In positive crankcase ventilating, air enters the
oil filler and breather cap, Fig. 10-1. The cap is
fitted with a copper mesh air filter that takes dust
out of the air. The filtered air is passed through
timing gear compartments into the crankcase at
crankshaft level. Unburned hydrocarbons are
picked up here and carried through an opening in
the rear of the cylinder block, between the lower
part of the crankcase and the valve lifter
compartment.
The fumes are then circulated in the valve lifter
compartment cover channel to a mounting point.
From here they pass through the connector and
hose to the ventilator valve. This valve opens
when the engine is running and directs fumes into
the carburetor throat, where they are added to the
normal fuel and air mixture and burned.
The positive crankcase ventilator valve is
pulled off its seat against spring tension by mani-
fold vacuum, Fig. 10-2. At various engine speeds
the manifold vacuum differs and the valve will
travel in its body allowing fumes to be admitted
to the engine.
Oil Filler
and
Breather Cap
Ventilator Valve
In time, hydrocarbon deposits accumulate on
the valve, causing it to stick in its travel or plug-
ging it so fumes cannot flow. The following engine
conditions can be encountered when the valve is
inoperative: When fumes cannot enter the engine,
breather backflow occurs and fumes remain in the
engine compartment. Sludge, varnish and acids
will develop in the crankcase. These corrosive
agents may cause premature wear on engine parts
and serious engine difficulty.
Carburetion problems will also occur when the
fumes are not properly expelled. This malfunction
creates poor idling conditions and engine stalling.
Even with a properly functioning positive crank-
case ventilator valve, rough idling may occur if
idle is adjusted too low. Proper engine idle ad-
justment with an accurate tachometer is essential
for the 1963 models.
The Cadillac positive crankcase ventilator valve
is not interchangeable with those of other engines.
Use of other than the proper valve may result in
breather backflow and engine damage.
The fuel tank on all 1963 Cadillac cars is
mounted against the lower surface of the trunk
compartment with two support straps. This type
of mounting allows easy removal from below
without disturbing sheet metal parts. Felt pads
are attached to the tank at the points where the
support straps are secured. These pads eliminate
the possibility of a rumbling noise when the trunk
lid is closed or when driving on a rough road.
The gasoline filler cap is located behind the
rear license mounting plate, which is the filler
door. The hinged plate swings out from the top.
The filler pipe is attached to the tank at the rear
center through a flexible hose connector. A vent
pipe at the front of the tank allows air to escape
from the tank when fuel is being added.
The tank, unit for the gasoline gage is mounted
near the top center of the fuel tank. It contains
the float unit, which is connected to the gage unit
on the instrument panel by one wire, with another
Connector
Spring
Fig, 10-1 Engine Ventilating System Fig. 10-2 Ventilator Valve