Cylinder Head Assembly: Description and Operation

Cylinder Heads and Valve Gear









Cylinder heads are unique to each cylinder bank and are secured, using deep seated bolts, to the cylinder block. Two hollow dowels align each cylinder head with the cylinder block.

Each cylinder head gasket consists of a silicon beaded composite gasket with metal eyelets for the cylinder bores.

Each cylinder head incorporates dual overhead camshafts operating four valves per cylinder via solid aluminum-alloy valve lifters. A steel shim in the top of each lifter allows adjustment of valve clearances.

Valve head diameter is 31 mm for exhaust and 35 mm for intake, and ail valve stems are 5 mm diameter. Valve seats and guides are sintered metal inserts.

Collets, valve collars and spring seats locate the valve springs on the intake and exhaust valves. Valve stem seals are integrated into the spring seats.

Four 14 mm spark plugs are located in a recess on the center-line of each cylinder head.

Camshafts

The chilled cast iron camshafts are each retained by five aluminum alloy caps - location numbers '0 to 4' for the intake camshaft and '5 to 9' for the exhaust, marked on the outer face of each cap.

A machined flat near the front of each camshaft enables the camshafts to be locked, using a special tool, during the valve timing procedure.

Camshaft Covers





The camshaft covers are made from vinyl-ester plastic; Bank 1 cover incorporates an outlet for the full load engine breather.

The Bank 2 cover incorporates the engine oil filler cap and an outlet for the part load engine breather. Identical oil separators are incorporated inside the top of each cover. Each oil separator comprises a wire gauze packing in an open ended enclosure below the breather outlet.