Sea Cadets

These are fitted to prevent the leakage of oil, gas or water. The cylinder head gasket may be made from copper and compressedfibre, or soft iron, whilst other joints are of treated paper or metal-tometal with joining compound between the mating faces

The fuel injection pump may be fitted on the side of the engine, or an individual fuel injection pump may be fitted alongside each cylinder. The pump is driven by the timing gear so that fuel is injected into eachcylinder at the correct time. Each cylinder head is fitted with an injector, which consists of

The camshaft must be accurately timed to the crankshaft so that the valves will open when required and for the correct period. The timing gear consists of gear wheels usually mounted at the front end of thecrankcase and enclosed by a timing case. The gear wheels are marked to show the correct setting.

All valve gear is fitted with tappets, a form of set screw and lock- nut, which may be fitted to the rockers. The tappets (marked valve clearance adjuster in the drawing below) are adjusted to give a slight clearance for expansion between the tappet and the valve stem. This clearance is always stated in the8

Overhead valves are operated by rockers with one end of each rocker bearing on the cam or push rod, and the other end on the valve stem. On overhead cam engines, rockers are not required, the valves will be operated directly by the camshaft.

Each valve, or pair of valves, is opened by a cam, which is pear shaped and machined in an angular position on the camshaft so that it will lift the valve forthe correct period. The camshaft may be above the cylinder head, the engine will then be known as an“overhead cam engine”. Alternatively, this may

The valves are fitted in the cylinder head and have a mushroom type shape. They have a long stem over which a spring is fitted to retain thevalves in their seats in the cylinder head. When open they allow the passage of air, and exhaustgas, when shut they seal the cylinder.

Most internal combustion piston engines have a heavy flywheel to carry the engine over the non-power strokes, particularly in the four-stroke engine where there is only one power stroke in four on each piston. The flywheel is attached to the crankshaft, and is outside the crankcase. The flywheel usually incorporates a toothed ring for the

The crankshaft is carried in main bearings which are part of the crankcase casting with laved bearing shells and caps securely bolted to the crank case. In some engines this is “under slung” in that the mainbearings are supported from the bottom of the cylinder block; in others these are supported in the bedplate. Most

The connecting rod is attached to the piston at one end by a gudgeon pin which is fitted to the piston. A bush in the end of the connecting rod provides a bearing surface. This is called the small end (or gudgeon pin or top end) bearing. The bottom end of the connecting rod is