Cadillac 54-6219 1954 Shop Manual page 233

ENGINE FUEL AND EXHAUST
GENERAL DESCRIPTION
The fuel tank on all 1934 Series CadiUac cars
is rilounted against the lower surface or the trunk
comps rtmel,t with two support straps and insulated
from the underbody with anLi-squesk. This provides
fur
easy remova] from below without diaL-u ri,ing
Any of he sheet metal parts.
The tank is constructed of two shallow pans,
square in shape, placed flange La flange and welded
around the entire flange. Ribs stamped into the pen
provide a rigid construction.
Two tuhes an. attached to the tank and join at
the upper end of the filter pipe. One allows air to
cecape from the rank when gasoline is
added.
The gasoline filler cap is located below the
hinged left rear tail lamp. as sho'sqt in Pig. 12-I.
The gasoline line is attached to the left front
corner of the tonk and exteilds along the left frame
side bar to the fuel pump. ]lj5 location permits
maximum cooling of the lines by outside air cur
rents and prevents vapor lock.
11,e fuel pump is mounted on the engine nil fi 'Icr
houeing. the pump push rod is driven by an eccen
tric, machined as an integra I part of the camshaft.
Fuel is drawo into thu fuel pump nn the dowoiward
stroke of the diaphragm as the rocker arm is
moved upward by 'he push rod.
Some engine operating conditions do nat necea
-
sitale full trave; of t]'c diaphragm in the fuel pump.
When this condition of fiLet pump sufficiency is
reached a separate sprijg and hit arrangement
keeps the rocker arm and push rod in contact.
A fuel filLer, connected between the fuel p*,lrnp
and the carburetor, receives fuel from Lhe pump
and filters out all dirt particles In exceaa of .UOI
in di a meter.
ntis removes a c a usc of flooding
and possible
c lagging of email passages in the
carburetor.
Either thin four-barrul Ruclicater Model 4CC or
Cutter Model VQC FE carburetor are used inter
changeably on 1954 engines. While both carhurc;o ra
differ in design, operatingprincipies and character
istics are similar. *]'he basic carburetion systems
of each carburetor are briefly described in the
following paragraphs.
Rochester Carburetor Circyits
The aochester Mode I 4GC Carburetor consists
basically of two dual carburetors. The two carbure
tors cull be referred to as Lhe Primary stde and
the Secondary side. The Primary side completely
controls the mete ring to the engine throughout the
idle and
ian
throttle ranges The Secndary Side
supplements the fuel and air frnm toe Primary
Side
throughout the idle aild [ower or wide open
throttle range.
Float System
To aid In maintaining lie correct fuel level
under all conditions of operation, twio sets of dual
floats are used,
Both sides of the carburetor incorporate indivi
dual floal systems for maintaining the proper fuel
level in each float bowl. All fuel enters the corhu
-
rotor on rue primary side.
As the fuel level drops, tIle dm1 floats also
drop, thus allowing ftiel pressure to move the inLet
needles off their seats. Pressure rroili the fuel
pump forces
fuel through the fiLter screen into
the inlet passage and the fiost bowl. As the fuel
level rises
*
the ftuats rise and furce the inlet
needles into their seats, closing the fuel paeaage.
Both sides
of the carburetor are individual
and internally
vented. These veta
transmit Tile
pressure from beneath the eir cleaner to the tad
In the float bowls. The amount of the fuel metered
by the carburetor is dependent upun the prussure
in the float howls causing fuel to flow.
To minimize
difficult hot wather starting or
tough idling, an external vent is incorporated which
opens oti
y
shcn the throtLle valves s re in the
clueS poeitio.
This externaJ idle vent con&iets
of an actuating lcvc r attached to the pump slia ft
and lover assembly, idle ven, valve, retainer, idle
12-2
Fig, 2-I GoiolEn Filk Cap