Cadillac 1937 LaSalle VVI Information page 191

103
E N G I N E
A n o t h e r precaution that should be observed i n
adjusting these carburetors is to make sure that
the hand choke control is fully released b y seeing
that the choke lever on the carburetor js up
against the stop.
Failure to observe these precautions will result
in an overlean mixture, which will invariably m a n i -
fest itself in backfiring in the muffler. In any
instances of back-firing, therefore, the first t h i n g
to be done is to readjust the carburetor w i t h the
thermostat blocked open, and the h a n d choke
fully released.
The idle speed of the engine should be set b y
means of the throttle adjusting screws to a speed
of approximately 320 R . P . M .
After the carburetor has been satisfactorily
adjusted in the idling position to a speed of
approximately 320 R . P . M . , the adjusting screw
should be turned slightly more toward the rich
side but not more than % of a turn. T h e car
operates more satisfactorily on a slightly rich
mixture than on a lean mixture, and this additional
Y\ of a turn toward the rich side w i l l help to
prevent any possibility of popping back.
After the throttle stop screw adjustment is
completed the automatic choke connection should
be released. T h e thermostat should not be t a m -
pered with. It is properly adjusted at the factory
and ordinarily requires no further adjustment.
If it has been tampered with, however, i t can be
adjusted by loosening the adjusting nut and slid-
ing the thermostat stop u n t i l a pull of 5.2 ounces
is required to hold the thermostat arm i n a hori-
zontal position. T h i s should be done at a tem-
perature of 70°F.
In case of continued popping back w i t h the
carburetor and the choke controls p r o p e r l y '
adjusted, the cause will usually be found in the
contact points or in the ignition timing. In
retiming the ignition, the flywheel t i m i n g indi-
cator should be set on or slightly ahead of the
I G / A ' mark. It should not be set behind the
• I G / A mark nor any more t h a n . J ^ i n . ahead of
the mark.
39. 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 e r i e s 37-85 a n d 9 0 — T h e adjustments of the
two carburetors on the series 37-85 and 90 engines
should be equalized to secure s m o o t h running of
the engine. T h e best method to follow is to use
an equalizing gauge. T h e gauge is connected to
the intake manifolds after the v a c u u m lines are
disconnected. T h e throttle rod must also be
disconnected from the right-hand carburetor.
' A preliminary adjustment of the metering pins
and throttle on both carburetors is then made to
bring the idling speed at approximately 320
R . P . M . T o determine whether or not the engine
is running at the correct idling speed, remove the
oil filler cap from one of the v a l v e covers and hold
a finger on one of the valve rocker arms so that
the movements of the rocker arm m a y be counted.
A t 320 R . P . M . the valve will open forty times
in fifteen seconds.
M a k e sure that the gauge hangs straight and
check the level of the mercury in the tube. W h e n
the metering pins and throttle stop screws are
properly adjusted, both columns of mercury
should be at the same height and the engine
should run smoothly at 320 R . P . M .
If the columns of mercury are not at the same
level and the engine speed is too fast, reduce the
speed b y backing off the throttle stop screw on
the side on which the mercury column is the lower.
If the speed is too slow, turn the throttle stop
screw i n a little on the side on which the mercury
column is higher.
Adjust the right-hand throttle control rod to
exactly the right length so that the clevis p i n can
be slipped into place without changing the engine
speed.
A further check should be made oh the throttle
adjustment b y running the engine at approxi-
mately 1000 R . P . M . and noting the mercury level
in the gauge. If the columns are not practically
level, a slight readjustment of the right-hand
throttle control rod will be necessary, F i n a l l y ,
run the engine again at idling speed and check the
mercury columns again. A very slight readjust-
ment of the throttle control rods may be necessary
to bring them to the proper level again.
If an equalizing gauge is not available, the
following method m a y be used to equalize the
carburetor adjustment.
Disconnect the coil wire for the right-hand
cylinder block. Adjust the metering pin of the
left-hand carburetor in the same manner as when
using mercury tube and set the throttle stop
screw so the engine will just t u r n over without
stalling.
T h e n disconnect the coil wire for the left-hand
cylinder block and adjust the metering pin and
the stop screw on the right-hand carburetor i n a
similar manner. W i t h the metering pins and
throttle stop screws on both carburetors properly
adjusted, the engine should idle at about 320
R . P . M .
The foregoing adjustment, m a y be slightly rich
when all cylinders are operating. T o correct
this, it m a y be necessary to screw u p slightly each
metering p i n adjustment. W h i l e testing the car
on the road the above adjustments should be
rechecked to be sure they are satisfactory.
40. C l e a n i n g C a r b u r e t o r A i r C l e a n e r
The. filtering unit of the carburetor air cleaner
on a l l 37-series cars should be serviced every
2,000 miles or oftener if extreme dust conditions
are encountered. T h e correct procedure for
servicing the cleaners on the different models is as
follows: