1938 Cadillac V16 - GM Heritage Center

12
Cadillac-LaSalle Preliminary Service Information
With the exception of piston pin removal,
service operations are unchanged from previous
practice. Bearing clearance limits are the same as
for V-8 bearings, and the replacement operations
are the same. Piston fitting is performed in the
same manner and with the same feeler gauges as
used for 37-85 and 90. Cylinder reconditioning is
performed in accordance with the instructions for
the V-8 en-block cylinders. Valve service operations
are the same as for V-8, except that it is
necessary to remove the valves before the valve
lifters can be removed.
Piston pins are removed by taking out the locking
screw, then spreading the split end of the
connecting rod with Tool No. J-1167, and tapping
the pin out of piston and rod with a brass drift.
To reinstall a piston pin, first spread the rod with
Tool No. J-H67, then assemble pin in piston and
rod in the correct position, as shown in Fig. 8.
Tap the pin into place and turn the locking screw
part way in before removing the spreading tool.
Fig. 8. Assembly of 38-90 piston and connecting rod
Two connecting rods are carried side-by-side on
each crankpin. Because of the short stroke, the
rods need to be only 6% inches in length. Use of
2-inch crankpins permits the removal of piston
and rod assemblies from above without the necessity
of an angle-split rod bearing.
The piston and connecting rod assembly is a departure
in one respect from previous Cadillac practice.
The piston pin is held in the rod by a locking
screw and rotates in the piston. With this construction,
shown in Fig. 8, snap rings for the pins
are not required, nor is it necessary to have a
drilled oil passage in the connecting rod to lubricate
the pin bushing.
Thc pistons are of the familiar T-slot design and
are made of aluminum alloy with anodized finish.
Two compression rings and one oil ring are used.
Two grooves are broached the full length of the
piston pin bearing to collect oil from the cylinder
wall and distribute it along the pin.
The valve mechanism in the V-16 engine is
basically the same as the V-8 design. The camshaft
is mounted on five bearings in alternate bulkheads
of the crankcase. It is located in the center
of the vee, directly above the crankshaft, and is
driven by a non-adjustable silent chain at the
front of the engine. An idler chain adjusting
sprocket, as used on 37-90, is unnecessary.
The cams operate valve lifters which include
hydraulic valve silencers of the same design as
used in V-8 engines. (See Fig. 9.) The valves
themselves are of the same materials as used in
V-8 valves but are smaller, with diameters of
and 1¾ inches for intake and exhaust, respectively.
Single valve springs are employed. The
entire mechanism is enclosed by two removable
covers placed across the top of the engine vee.
Oiling System—The engine oiling system is
similar to that of the V-8 engines, but of much
greater capacity. Eleven quarts of oil are carried
in the pressed steel oil pan.
Oil is drawn from the pan through a floating
intake to the gear-type oil pump which is attached
to the crankcase at the rear of the engine. A
piston type oil pressure regulator is incorporated
in the pump body. The pump is driven by a
vertical shaft which has at its upper end a gear
meshing with a gear integral witn the camshaft.
(See Fig. 9).
From the pump, oil passes to a header that runs
full length of the crankcase. Drilled passages in
the bulkheads connect the header with the main
and camshaft bearings, and drilled passages in the
crankshaft carry oil to the connecting rod bearings.
The rear main bearing oil seal is of the same
type as used in the 38-series V-8 engines. (See
Fig. 5, Page 9.)
Fig. 9. Hydraulic valve lifters are used in the 38-90 engine