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75
G A S O L I N E S Y S T E M — G e n e r a l D e s c r i p t i o n — S e r v i c e I n f o r m a t i o n
nozzle into the m i x i n g chamber.
T h e fuel in the
pump cylinder cannot escape back into the float
chamber because of the check valve in the bottom
of the pump cylinder.
In general—for steady d r i v i n g conditions up to
60 miles per hour on level roads the fuel is all
supplied from the aspirating tube.
When
the
throttle is opened suddenly an additional charge
of fuel is supplied from the accelerating pump,
and if the throttle is held open as for hard pulling
or high speed, extra fuel continues to flow from
the pump discharge nozzle through the power jet.
F U E L
P U M P
The fuel feed o n all models is by a fuel pump.
This pump is operated by a push (driving) rod
riding against a c a m on the distributor shaft and
is located at the front of the engine on the left,
in the coolest position under the hood.
T h e principal m o v i n g element of the fuel pump
is a diaphragm actuated through a series of levers
and rods as shown in F i g . 2, Plate 40. The opera-
tion is as follows.
W h e n the push rod is moved
in and out by the action of the d r i v i n g cam, it
in turn operates the rocker arm which is pivoted
at the lower end.
T h e rocker a r m pulls the pull
rod and diaphragm assembly down, creating a
vacuum in the p u m p chamber which draws gaso-
line from the rear tank into the sediment bowl
and through the strainer and inlet valve into the
pump chamber.
The diaphragm is m o v e d u p w a r d on the return
stroke by pressure of the diaphragm spring.
O n
this stroke the-gasoline is forced from the pump
chamber through the outlet valve, into the vapor
dome ancl thence to the carburetor.
W h e n the carburetor bowl is filled and the inlet
needle valve closes, a back pressure is created in
the fuel pump chamber.
This pressure holds the
diaphragm
down
against
the .pressure of
the
diaphragm spring, a n d keeps it i n this position
until more fuel is needed in the carburetor and the
needle valve opens.
The rocker a r m is in two pieces, operating as a
single part when the diaphragm is working up
and clown.
However, when fuel is not required
and the link or lower part of the operating lever
is held down at one end by the diaphragm pull
rod. the lever or upper part operates in the usual
way.
T h i s is made possible by the fact that the
lever operates against the link only in the down-
ward direction, the u p w a r d movement of both
parts being accomplished by spring pressure.
A
second spring is provided for keeping the lever in
contact with the d r i v i n g rod .at all times.
I N T A K E
S I L E N C E R
A n intake silencer is used on all models.
T h e
silencer silences the roar of the intake at certain
engine speeds under open throttle.
There arc no
moving parts or baffle plates on these silencers and
they require no attention in service.
A feature of the air silencer is the copper gauge
air cleaner which is designed to catch any dust or
lint in the air before it is drawn into the carburetor.
It is automatic
in operation and requires
no
attention other than periodic cleaning.
S e r v i c e I n f o r m a t i o n
1. G a s o l i n e G a u g e A d j u s t m e n t
If the gasoline gauge does n o t register c o r r e c t l y a n d the
v a r i a t i o n from a c c u r a c y is the same o v e r the entire scale, a
readjustment
of the float o n the t a n k
u n i t should
correct
the trouble.
T h e float a d j u s t i n g screw at the side of the lloat
rod gear is accessible, if the t a n k u n i t of the gauge s y s t e m is
removed from the t a n k .
A c c u r a t e readings between 0 a n d 4 gals, should not
be
expected.
7. E q u a l i z i n g C a r b u r e t o r A d j u s t m e n t s - - 3 7 0 - B , 4 5 2 - B
T h e adjustments of the two carburetors on the 370-B a n d
452-B cars s h o u l d be equalized t o secure s m o o t h r u n n i n g of
the engine. T h e best m e t h o d to follow is to use an e q u a l i z i n g
gauge as shown in F i g . 4, P l a t e 39.
The gauge is connected
to the intake m a n i f o l d s after b o t h the brake assister
a n d
v a c u u m lines arc disconnected.
T h e throttle rod must also
be disconnected from the r i g h t - h a n d carburetor.
A p r e l i m i n a r y a d j u s t m e n t of the metering pins a n d throttle
on b o t h carburetors is then made to b r i n g the idling speed at
a p p r o x i m a t e l y 320 R . P . M .
T o determine whether or not the engine is r u n n i n g at the
correct i d l i n g speed, remove the o i l filler cap Irom one o l the
valve covers a n d h o l d a finger o n one of the v a l v e rocker a r m s
so that the m o v e m e n t s of the rocker a r m m a y be counted.
A t 320 R . P . M . the v a l v e w i l l open forty times in
fifteen
seconds.
M a k e sure t h a t t h e gauge hangs straight a n d check the
level of the m e r c u r y i n the tube.
W h e n the metering pins
a n d t h r o t t l e stop screws are p r o p e r l y adjusted, b o t h c o l u m n s
o f m e r c u r y s h o u l d be a t the same height a n d the engine s h o u l d
run s m o o t h l y at 320 R . P . M .
If the c o l u m n s of m e r c u r y are not at the same level a n d
the engine speed is too fast, reduce the speed b y b a c k i n g off
the throttle stop screw o n the side o n w h i c h the m e r c u r y
c o l u m n is the lower.
1 f the speed is too slow, t u r n the throttle
stop screw in a l i t t l e o n the side o n w h i c h the m e r c u r y c o l u m n
is higher.
I f the m e r c u r y c o l u m n s are at the same level a n d the engine
speed is too fast o r too s l o w , adjust b o t h throttle stop screws,
t u r n i n g t h e m e x a c t l y the same a m o u n t to secure the correct
i d l i n g speed, at the same t i m e keeping the m e r c u r y c o l u m n s
at the same level.
R e - c h e c k the m e t e r i n g p i n adjustments
a n d i d l i n g speed
on b o t h carburetors, m a k i n g sure t h a t the m e r c u r y c o l u m n s
are m a i n t a i n e d at the same level.
A d j u s t the r i g h t - h a n d t h r o t t l e control rod to e x a c t l y the
r i g h t length so t h a t the clevis p i n c a n be s l i p p e d into place-
w i t h o u t c h a n g i n g the engine speed.
A further c h e c k s h o u l d be m a d e o n the t h r o t t l e
a d j u s t m e n t
b y r u n n i n g the engine at a p p r o x i m a t e l y 1000 R . P . M . a n d
n o t i n g the m e r c u r y level in the gauge,
i f the c o l u m n s arc not
p r a c t i c a l l y
level, a s l i g h t readjustment
of the
r i g h t - h a n d
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