Replacing Timing Chain And Sprockets; Removing V-12 And V-16 Camshafts; Removing And Installing Valves - Cadillac 1937 LaSalle VVI Information

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E N G I N E
engines is similar to that of V - 8 engines, except
for the difference in engine size and construction
and that no special tools are required.
18. Removing V-12 and V-16 Camshafts
When removing the camshaft from series 37-85
and 90 engines, the v a c u u m pump and the dis-
tributor drive shaft must both be removed before
any attempt is made to draw out the camshaft.
T h e gear on the distributor drive shaft meshes
with a gear on the camshaft. T h e driven gear
would be damaged by striking against the blank
sides of the camshaft gear if an attempt was made
to remove the camshaft [first. R e m o v i n g the
camshaft w i t h the vacuum p u m p in place would
permit the pump d r i v i n g rod to fall into the
crankcase.
19. Replacing Timing Chain and Sprockets
Series 37-50, 60, 65, 70 and 75
Engine t i m i n g chains and sprockets should be
installed as a unit. Care should be exercised to
see that the timing marks are properly lined up
as shown i n Plate 31.
Pilot, T o o l N o . J-836, should be used on the
end of the camshaft when installing the chain and
sprockets. D o not attempt to force the camshaft
sprocket on the shaft, as this might damage the
distributor and oil pump drive gear or the rear
camshaft bearing.
T h e front cover plate gasket of all V - 8 engines
is an open end gasket, but for easier handling is
supplied w i t h a closed end. W h e n installing this
gasket, therefore, tear off the lower portion as
shown in Plate 31, F i g . 20.
Series 37-85 and 90—The timing chains and
sprockets used on the V-12 and V - 1 6 engines are
similar in design and construction. Installation
of the chain and setting of the automatic adjusting
mechanism for eliminating any free play that may
develop in the chain is shown in Plate 32.
A l l 37-series V-12 and V-16 engines are equipped
with a t i m i n g chain dampener to prevent chatter
in the automatic chain adjuster b y lessening the
amount of chain whip at moderate speeds. Proper
adjustment of the dampener, which is located on
the oil pressure relief valve body, is essential to
quiet engine performance.
The t i m i n g chain dampener may be adjusted
by loosening the screws b y which it is attached to
the.relief valve body and shifting it through the
clearance provided i n the screw holes. A d d i t i o n a l
movement m a y be obtained, if necessary, b y
loosening the relief v a l v e attaching screws and
shifting'the entire valve as desired.
A s shown in Plate 32, F i g . 23, the dampener
should be adjusted to give .015" clearance top.
and bottom between the face of the dampener and
the timing chain. If the angle of the dampener is
not sufficient to give the desired clearance, it m a y
be increased b y bending the dampener i n a vise.
20. Removing and Installing Valves
T o remove the valves from series 37-50, 60, 65,
70 and 75 engines, it is necessary first to remove
the valve lifter assemblies. T h e valve spr ng
keepers can then be removed by compressing the
springs w i t h valve lifter J - 2 5 7 - X . (See Plate 34).
T h i s valve lifter is also used for installing the
keepers when reinstalling the valves.
Before reinstalling the valve lifter assemblies,
the valve stems should be checked for proper
length using the valve stem length gauge J-1055,
see Plate 34, F i g . 30, If the valve stems are
found to be too long when checked in the closed
position, they should be ground off u n t i l the tool
will slide into place.
Installation of the lifter assemblies is greatly
facilitated by the use of tool J-827, which holds
the tappet plungers down.
Illustrated instructions for removing and install-
ing series 37-85 and 90 overhead valves are given
in Plate 35.
21. Valve Silencer Operation
Series 37-50, 60, 65, 70 and 75—The design
and construction of the hydraulic valve lifter
mechanism used on all 37-series V - 8 engines is
shown in Plate 33.
T h e manner in w h i c h these valve lifters operate
is as follows: O i l is forced under pressure directly
to each tappet, b o d y through the longitudinal
passageway drilled in the valve guide casting.
F r o m this passageway o i l enters the chamber
inside of the valve lifter body through a small
hole leading into the plunger cylinder. T h e o i l
pressure opens the ball check valve, F i g . 28 in the
inner cylinder, permitting o i l to pass into the
space in the .cylinder below the plunger.
W h e n the cam brings the valve lifter up
against the resistance of the valve spring, the
oil i n the inner cylinder is trapped b y the ball
' check valve. T h i s prevents the plunger from
sliding down i h t o \ h e cylinder, and w i t h the valve
lifter spring keeping the plunger in contact w i t h
the valve stem at all times,, zero clearance is
maintained between the stem and lifter, providing
silent valve operation.
Series 37-85 and 90 -j- T h e design and con-
struction of the automatic .Valve silencer mechan-
ism used on the 37 series V-12 and V-16 engines
is shown in Plate 35.
T h e manner i n w h i c h these v a l v e silencers
operate is as follows: E a c h rocker arm for the
overhead valves is mounted on a flanged eccentric
bushing. Located directly below the flange of
this bushing is a dash pot, the plunger of which
bears against a cam on the flange at all times.
U p w a r d pressure of the spring under the plunger
keeps the eccentric in such a position that the
rocker a r m always touches both the valve stem
and the push rod.