ENGINE <NON-TURBO>
-
Base Engine
l-3
BASE ENGINE
L
CYLINDER HEAD
Features a Dual Over Head Camshaft (DOHC)
4-valves
per cylinder cross flow design. The valves
are arranged in two
inline
banks. Incorporated
pow-
CYLINDER BLOCK AND BED-PLATE
Five different engine designs were considered, the
only engine design that met all the criteria was one
that utilized a bed-plate. There are several forces
at work in the lower end of an engine block.
These are:
l Vertical bending
l
Horizontal bending
-
90 degrees to the cylinder
bore
l
Torsional bending along the crankshaft axis
l
Individual main cap flutter co-inciding to indi-
vidual cylinder firing
All these factors contribute to noise, vibration and
harshness. Because this is a four cylinder engine,
design criteria becomes even more important.
Bed-
PISTON
The piston has an oval shape (elliptical) that expands
as the engine warms-up. This reduces cold engine
id
piston noise, helps the piston fit into the bore better
and avoids piston scuffing.
The piston pin has a 1 mm
(.0394
in.) offset toward
the thrust side of the piston for improved noise char-
acteristics. The top ring is a steel unit with a plasma
sprayed molybdenum faced center section for reli-
able compression sealing. The upper ring is not
directional. The black coating as a rust preventative.
A taper faced cast iron second compression ring
N71ABOlAA
der metal valve guides and seats. Integral oil galleys
within the cylinder head supplies oil to the hydraulic
lash adjusters, camshaft and valve mechanisms.
N7lAB02AA
plate design makes for a much stronger lower end
because it ties all of the main caps together to sub-
stantially improve block stiffness. The block is a
two-piece assembly, encompassing the bed-plate
and the cylinder block. The bed-plate is made of
cast iron and is totally separable from the block.
When installed, it becomes part of the block and
strengthens the lower end considerably. The
bed-
plate and block are cast separately, then machined
together. Once machined, the bed-plate and block
are drilled and doweled together to become a mated
unit. This ensures that the bed-plate and block are
in perfect alignment even after assembly and disas-
sembly.
N7lAB03AA
is used for additional cylinder compression control.
Both compression rings are 1.2 mm
(.0472
in.) thick.
The oil ring is a three piece design using chrome
faced fails and a separate center expander. Use
the running clearance notches and is identifiable
by a slight dish at the top of the piston.
This engine is pressed-in piston pins to attach forged
powder metal connecting rods. Incorporate hex head
cap screw threaded into the connecting rod. Piston
and Rods are serviced as an assembly.
I
/
No. 1 piston ring
No.
2
piston ringJ
1
1
\
L
Side
rail
extender
Oil ring
CENO066
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