1938 LaSalle Production - GM Heritage Center

new plugs if the old plugs are badly worn. A.C. Spark
Plug Model 45 is recommended for Cadillac V-8 cars.
Cleaning the timer contact points in the distributor and
setting to a gap of .012-.018 inch. Replace contact points if
they are badly worn.
Retiming the ignition to the timing marks on the harmonic
balancer at the front of the engine.
Carbon and Detonation—Most automobile owners
have been taught that a detonation or "ping" in the engine
is an indication of an over-advanced spark or of carbon in
the engine, and probably the latter. While this is true, the
following supplementary information must be included when
considering "ping" in any high compression engine.
On cars with high compression engines, slight detonation
occuring on rapid acceleration at low speeds and disappearing
at about 15 miles per hour, is normal and indicates that
the engine is performing at top efficiency. Detonation at
higher speeds can be eliminated by checking and correcting
the following:
Grade of gasoline used—The Series 60 and 65 engines are
designed for use with 70 octane gasoline (regular); the Series
75, for premium fuels. Gasoline of a lower rating may be
used safely, but in this case the ignition timing must be
retarded to a point where the engine will not knock.
Over-lean mixture—This may be due to an incorrect
carburetor adjustment or to an obstruction in the fuel feed.
Spark plugs—One or more faulty spark plugs will cause
pre-ignition in their respective cylinders. Replace these
with A. C. model 45 spark plugs.
Accumulation of Carbon—Accumulated carbon must be
removed by scraping after taking off the cylinder head.
Removal of carbon by burning is not recommended.
Carburetor — The only adjustment required by the
carburetor is the idling adjustment.
The idling speed should be set with the throttle stop
screws to the equivalent of 6 miles per hour. The two idle
needle valves should then be adjusted until the engine runs
smoothly. These adjustments must be made when the engine
is hot.
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Any adjustments to the automatic choke mechanism
should be made only at an Authorized Service Station.
Air Cleaner—-Your Cadillac car is fitted with an air
cleaner of the "oil bath type," which operates very efficiently
in removing dust from the air drawn into the engine. As
this type of cleaner accumulates considerable dust and
dirt, it requires regular cleaning every 2,000 miles, or
oftener if extreme conditions are encountered.
The cleaner is cleaned and re-oiled in the following
manner:
Remove the gauze unit and wash thoroughly
in gasoline, taking particular care to wash all
the accumulated dirt and dust out of the wire
mesh.
Dry all the units thoroughly, either with
compressed air or an adequate drying period.
Pour one pint of S.A.E. 50 engine oil (S.A.E.
40 in winter) in the reservoir and assemble the
wire mesh and cap.
NOTE: No oil should be placed on the wire
mesh.
Gasoline Filter—A gasoline filter is provided at the
fuel pump on the front left hand side of the engine. Any
accumulation of water or sediment should be cleaned out
when it can be seen in the glass bowl. Remove the bowl by
unscrewing the thumb nut and swinging the yoke to one
side. If the screen strainer sticks, remove it by pulling
straight down.
Any dirt on the strainer should be washed off with gasoline,
and the bowl should be wiped clean. Then reinstall
screen and bowl, making sure the bowl seats properly against
the cork gasket and tighten.
Other Service Operations—Major service operations
on the engine, such as valve grinding, replacement of bearings
or reconditioning of cylinders, should be performed only by
experienced workmen having the necessary instructions and
equipment.
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