Engine: Description and Operation

BLOCK
The cylinder block is a partial open deck design to improve cooling and weight reduction. High rigidity is provided with ribs cast in the outer wall, and a monoblock or beam type main bearing cap system. This single unit four bearing cap is designed to control vibration of the cylinder block partition walls.

CRANKSHAFT
The crankshaft is made of nodular cast iron and has six individual throws with five counter weights, it is supported by four main bearings with number three being the thrust bearing. The six separate connecting rod throws pins reduce torque fluctuations while a dynamic damper is used to control torsional vibration of the crankshaft. Rubber lipped seals are used at front and rear. The front seal is retained in the oil pump case and the rear is retained in a diecast aluminum block-mounted housing.

PISTONS
Are aluminum alloy with cast in steel struts at the pin bosses for autothermic control. The piston head is designed with valve recesses to provide for valve clearance. The piston rings consist of a chrome-plated, barrel faced design for the top ring, the second ring is a cast iron tapered face design and the oil ring is a chrome faced three piece design. Piston pins are press-fitted into place, to join the pistons to the forged steel connecting rods. The large end of the connecting rod has a oil jet hole for lubrication of the thrust side of the cylinder.

CYLINDER HEAD
The aluminum alloy cylinder heads feature a pent-roof design with four valves per cylinder. Valve guides are made of cast iron alloy and seat inserts are made of sintered alloy iron, these are pressed into the head. To improve combustion efficiency the chambers have a compact pent-roof design with a squish area. The cylinder heads are common to either cylinder bank.

CAMSHAFTS
Two overhead camshafts provide valve actuation, one left (radiator side of cylinder bank) and one right. The distributor is directly driven by the right camshaft. Both camshafts are supported by four bearing journals integral with the head. A flange at the rear of the camshaft acts as a thrust collar. Right and Left camshaft driving sprockets are interchangeable. The sprockets and the engine water pump are driven by the timing belt.

ROCKER ARM SHAFTS
The shafts are retained by retaining caps and bolts. Four shafts are used, one for each intake and exhaust rocker arm assembly on each cylinder head. The hollow shafts provide a duct for lubricating oil flow from the cylinder head to the valve mechanisms. Rocker shaft springs are use on the intake shafts ONLY to obtain the proper clearance between the intake rocker arms and the spark plug tubes.

ROCKER ARMS
Are of light weight die-cast with roller type follower operating against the camshaft. The valve actuating end of the rocker arms are machined for hydraulic lash adjusters, eliminating the need for periodic valve lash adjustment.

VALVES
Four valves per cylinder are actuated by die-cast aluminum roller rocker arms and hydraulic lash adjusters assemblies which pivot on rocker arm shafts. All valves have 6 mm diameter chrome plated valve stems. The valve train has 33 mm (1.299 inch) diameter intake valves and 29 mm (1.141 inch) diameter exhaust valves. The valves have a carbo-nitriding finish for long life. Fluorcarbon valve stem seals are used on both valves. Stamped steel valve spring seat, Valve springs, spring retainers, and locks are conventional.

INTAKE MANIFOLD
This system is composed of an upper plenum (surge tank) and manifold. This aluminum alloy manifold has long runners to improve inertia. The plenum chamber (surge tank) absorbs air pulsations created during the suction phase of each cylinder. The lower intake manifold is machined for six injectors and fuel rail mounting.

EXHAUST MANIFOLDS
Both manifolds are made of cast nodular graphite iron for heat resistance. Exhaust gasses from the left cylinder bank, leave the left manifold through a stainless steel pipe and bellows routed under the engine to the right side manifold. The collected exhaust from both manifolds are combined, and exit to the exhaust pipe through a flex-join