1938 LaSalle Production - GM Heritage Center

soft, inexpensive cylinder block iron that the material
will not resist the hammering of valves in their seats,
hence have to use valve seat inserts.
Additional features of great strength result from
shortness, greater width and compactness made possible
by V-type design. A boss, Or column, extends
from the center of each cylinder block top face to the
crankcase which ties the unit firmly together.
Cylinder wall thicknesses are carefully checked in
all directions with an electric gauge. Cylinder walls are
triple-honed which imparts a smooth, glass-like finish.
This increases piston ring life, minimizes scoring possibilities,
promotes even cooling, and, therefore, increases
engine efficiency and long life.
Each bore is measured with an electric expanding
gauge and graded into one of thirty sizes. Pistons are
likewise weighed and graded into thirty sizes. This
permits an exact selective fitting of piston-to-bore to
.00007 inches variation in clearance. It insures maximum
operating efficiency of the engine.
Cylinder Head
The cylinder head is cast of the same material as the
block to insure uniform expansion of the two units
when heated. This avoids development of leaks and
gasket troubles prevalent in engines with cylinder heads
which differ in material from the block. The head is
light in weight for flexibility which provides a better
seal at the union with the block. This also reduces
cylinder bore and valve seat distortion.
The compression ratio for V-8 engines employed in
LaSalle, Sixty and V-8 is 6.25 to 1. This high standard
ratio permits the use of standard grades of fuel
without development of pinging noises.
The Fleetwood has a 6.7—1
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compression ratio