THEORY OF OPERATION
ENGINE COMPONENTS (Continued)
Crankcase (Cylinder Block):
The crankcase is a solid metal (aluminum) casting that makes up the bulk of the engine. The
cylinder mounting holes and various oil passages are bored in the block. It is a one-piece
aluminum casting with forged aluminum main bearing caps.
Seven main bearing caps function as an integral part of the crankcase. Each cap is secured
with four studs and four slotted nuts in addition to two through bolts that clamp the main
bearing cap in the crankcase. With this type of crankcase and bearing cap construction,
uniform load distribution in the bearing area is obtained making possible uniform distribution
of combustion forces over the entire crankcase.
Main bearing caps must be kept in their original location. They are
numbered 1 through 7 beginning at the front (damper) end of the
crankcase. The caps are secured to the crankcase before being line-
bored making them an integral component of the crankcase.
The seven replaceable main bearings are steel-backed, split type, having copper-lead alloy
bearing surfaces. The center main bearing is double-flanged with bearing material to control
crankshaft endplay and thrust.
Main Bearing Caps
WP 0004 00-13