PISTONS AND CONNECTING RODS
DESCRIPTION
The pistons are made of a high strength aluminum
alloy. Top land height has been decreased to reduce
emissions. Piston skirts are coated with a solid lubri-
cant for scuff resistance. Connecting rod is forged
steel with a squirt hole and attaches to the piston
with a full floating pin retained by lock rings.
CYLINDER HEAD
DESCRIPTION
The aluminum alloy cylinder heads feature cross-
flow type intake and exhaust ports. Valve guides and
seat inserts are powdered metal. Valves are arranged
in a “V”, with each camshaft on center. To improve
combustion speed the chambers are a compact spher-
ical design with a squish area of approximately 30
percent of the piston top area. The cylinder heads are
common to either cylinder bank by reversing the
direction of installation.
VALVES
DESCRIPTION
Valves are made of highly heat-resistant steel and
are chrome plated to prevent stem scuffing. The
intake valve is a one-piece forging, while the exhaust
valve has a forged head with a welded stem for lock
groove hardenability. The four valves (two intake and
two exhaust) employ a three-groove lock design to
help facilitate valve rotation.
OPERATION
The intake valve allows the air/fuel mixture to
enter the combustion chamber. The exhaust valve
allows the burned air/fuel mixture to exit the com-
bustion chamber. Also, the intake and exhaust valves
seal the combustion chamber during the compression
and power strokes.
VALVE SPRINGS
DESCRIPTION
Valve springs are unique for intake versus exhaust.
Both are made from chrome silicon alloy wire and
incorporate a “bee-hive” design. Valve spring retain-
ers and locks are common from valve-to-valve. The
valve spring seat is integral with the valve stem oil
seal, which incorporates a garter spring to maintain
consistent lubrication control to the valve stem.
OPERATION
The valve spring returns the valve against its seat
for a positive seal of the combustion chamber.
TIMING DRIVE SYSTEM
DESCRIPTION
The timing drive system (Fig. 5) has been designed
to provide quiet performance and reliability to sup-
port a NON free-wheeling engine.
The timing drive components include a crankshaft
sprocket, camshaft sprockets, tensioner pulley,
hydraulic tensioner and a timing belt. The water
pump is driven by the back side of the timing belt.
The right and left camshaft sprockets are not inter-
changeable because of the cam sensor pick-up wheel
on the left sprocket.
9 - 78 3.2/3.5L ENGINE LH
DESCRIPTION AND OPERATION (Continued)
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