1942 - 1947 CHEVROLET SHOP MANUAL
Section 6 - Engine
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6-34 |
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Idling Adjustment
Adjust the
carburetor idle and throttle stop screws in combination with each other to
secure the best idling
performance. Engine idling speed should be set at 450 to 500
R.P.M.
Cooling System
Tighten all cooling system hose
connections and examine for any
indications of water leaks. Check the fan belt for proper tension and adjust
it if necessary. Proper tension
is 1-1/2" total play up and down at a point between the water pump and
generator
pulleys.
Current and Voltage Regulator
Check the
adjustment of the current and voltage regulator according to the instructions
given in Section 12 of this
Manual.
Road Test
After
completion of the above operations, the car or truck should be road-tested
for performance. During this test the octane selector should be adjusted for the grade of gasoline being
used. For peak performance and maximum gasoline economy, the octane selector should be set
to pro- |
duce a slight engine "ping" on
acceleration at wide-open
throttle. |
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FUEL SYSTEM |
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CARBURETOR |
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The
downdraft carburetor on Chevrolet cars and conventional trucks contributes to the
smooth, quiet operation and
power of the Chevrolet valve-in-head engine. Downdraft, as the name
implies, means that the gas mixture is drawn down into the intake manifold rather than up from the
carburetor into the intake manifold as is done in the up-draft carburetor.
The downdraft embodies a principle
which em-ploys three Venturis, one
located above and two below the level of the gasoline in the float
chamber. This triple venturi has the effect of increasing the
suction on the first or primary venturi, causing the nozzle to start delivering gasoline at
very low air speeds. The
nozzle enters the primary venturi at an angle, discharging upward against
the air stream. This angle
provides an even flow of correctly proportioned and finely atomized
fuel.
The
gasoline thus atomized in the primary venturi is kept centrally located in the air
stream by |
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Fig. 71—Diagrammatic View of Downdraft
Carburetor |
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