1938 LaSalle Production - GM Heritage Center

conical spring at the bottom of each pipe prevents
exhaust gases from being blown into the crankcase.
A third pipe leads from the crankcase through the
rear valve chamber and up through the valve chamber
cover. Above the cover this pipe connects with the
vacuum line leading from the vacuum pump to the
intake manifold.
The ventilating system operates in two distinct
manners. At low speeds or part throttle operation, air
enters the crankcase through a number of holes from
three points, through both of the two pipes between the
air cleaners and valve chamber covers and through the
filter protected oil filler pipe. After the ventilating air
has mixed with the crankcase oil mist, absorbing water
and fuel vapors, a substantial vacuum draws it out
through the intake manifold.
At high speeds or with throttle open, intake vacuum
decreases but there is a rapid rush of air through the
carburetor air cleaners. This creates a suction in the
two pipes connecting them to the valve covers. Air
enters the oil filler as before, passes directly to the
crankcase, but the outward flow is reversed, the air and
impurities going into the valve compartments. The air
is then drawn upward into the air cleaners.
The system is simple and reliable in operation and
insures an adequate ventilation of the crankcase under
all conditions that is not equalled by any other method.
FUEL SYSTEM
From the 26.5 gallon tank fuel is drawn forward through
a single pipe placed in a cool position on the outside of
the right hand frame sidebar. Near the front of the
frame this pipe branches, one lead passing to the right
hand fuel pump and one crossing in front of the front
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