1938 Cadillac V16 - GM Heritage Center

Cadillac-LaSalle Preliminary Service Information 9
Engine
38-50 38-60 & 6$ 38-75
Bore and stroke 3¾ x 4½" 3½ x 4½" 3½ x 4½"
Piston displacement 322 cu. in. 346 cu. in. 346 cu. in.
Taxable H. P 36.45 39.20 39.20
Compression ratio 6.25 to 1 6.25 to 1 6.70 to 1
V-8 Engines
The 38-series V-8 engines incorporate a number
of refinements but are otherwise unchanged from
the corresponding previous series. There have
been no changes in engine sizes, but the power
output of the 38-75 engine only has been increased
by raising the compression ratio from 6.25 to
6.70. The 38-75 engine will therefore require the
use of ethylized or other high octane fuel.
This change in compression ratio does not
seriously affect parts stock requirements, as the
higher ratio on 38-75 is secured by using the same
cylinder head as used on 38-50 engines. The
markings on production cylinder heads must be
understood, however, to avoid confusion. They
are as follows:
Right-hand cylinder heads on both 38-50 and
38-75 engines are marked *322-625 and 346-680,
whereas left-hand cylinder heads on 38-50 arc
marked 322-625 and on 38-75 are marked 346-680.
Cylinder heads supplied by the Parts Division,
however, will be marked with both ratios regardless
of whether they are right or left hand heads.
crankshaft by a steel disc that permits a certain
amount of bending. On both sides of the supporting
disc are damping plates which press against
it. (See Fig. 4.)
The flexible flywheel web on the new Cadillac
design permits the rim to run in a true plane
regardless of crankshaft deflection. As the crankshaft
bends, the damping plates rub against the
flexible web, absorbing energy and damping any
bending motion of the crankshaft.
This type of flywheel requires no attention
whatever in service.
Fig. 5.
Rear main bearing oil seal used on all 38-series
engines
Fig. 4. "Damped bending" flywheel used on 38-60, 65 and
75 V-8 engines
An entirely new "damped bending" flywheel is
used on 38-60, 65 and 75 Cadillac engines. This
device eliminates crankshaft bending vibration
just as a torsional vibration dampener eliminates
torsional vibration.
The new flywheel, instead of being the usual
rigid casting, has a cast iron rim attached to the
•Piston displacement and compression ratio. (346-C80 will be changed to 346-670)
A positive rear main bearing oil seal (Fig. 5)
supersedes the former seal. The new design consists
of an asbestos composition packing, against
which the crankshaft turns, which is held in place
in the crankcase and bearing cap by sheet metal
retainers. This feature cannot be installed on previous
V-8 engines as changes in the crankcase and
crankshaft are involved.
Several detail changes have been made in the
engine oiling system. The use of an oil filter for
the V-8 hydraulic valve silencer supply has proved,
on the 37-series engines, to have slight advantage;
the oil filter has therefore been discontinued on
38-series V-8's. The oil pan drain plug has been
moved to the left side to improve accessibility
and increase road clearance. A flexible oil level
indicator plunger has been made necessary by the
new front opening hood.
Other changes in the V-8 engines include larger
generator drive pulleys to decrease belt flexing, a
more compact air cleaner and silencer assembly,
the use of thrust type distributor head terminals,
and rearranged high tension wiring.