0439516 EVINRUDE PISTON & RING ASSY., Stbd., 0.020 in. O.S.

Illustration 1 g01451294 Cylinder liners (1) are seated on a ridge (4) in the middle of the cylinder wall between the crankcase and the coolant jacket. The ridge is created by a counterbore in the cylinder block. The cylinder liners have a lip (2) which rests on the ridge. The seals of the coolant jacket are located in the upper regions and middle regions of the cylinder liners. The lower barrier uses a D-ring seal (3) that is located above the seating surface of the cylinder liner. The upper barrier is the head gasket which is above the coolant jacket.The cylinder block has seven main bearings in order to support the crankshaft. Each main bearing cap is fastened to the cylinder block with two bolts.Pistons, Rings, and Connecting Rods
The high compression ratio of the engine requires the use of steel one-piece pistons. The pistons have three rings:
Compression ring
Intermediate ring
Oil ringThe rings are located in grooves in the piston. The rings seal the crankcase from the combustion gases and the rings also provide control of the engine oil. The design of the compression ring is a barrel face with a plasma face coating. The design of the intermediate ring is a tapered shape and a chrome finish. The oil ring is double railed with a coil spring expander. The oil ring has a ground profile and a chrome finish.The connecting rod is a conventional design. The cap is fastened to the shank by two bolts that are threaded into the shank. Each side of the small end of the connecting rod is machined at an angle of 12 degrees in order to fit within the piston cavity. This allows a larger surface area on the piston, and connecting rod in order to minimize bearing load. Crankshaft
The crankshaft converts the linear motion of the pistons into rotational motion. The crankshaft drives a group of gears (front gear train) on the front of the engine. The front gear train provides power for the following components:
Camshaft
Water pump
Engine oil pump
Air compressor
Fuel transfer pump
Accessory driveThe crankshaft is held in place by seven main bearings. The oil holes and the oil grooves in the shell of the upper bearing supply oil to the connecting rod bearings. The oil holes for the connecting rod bearings are located at the following main bearing journals: 2, 3, 5 and 6.Hydrodynamic seals are used at both ends of the crankshaft to control oil leakage. The hydrodynamic grooves in the seal lip move lubrication oil back into the crankcase as the crankshaft turns. The front seal is located in the front housing. The rear seal is installed in the flywheel housing.Camshaft
Illustration 2 g00762808The camshaft has three lobes at each cylinder in order to operate the unit injector, the exhaust valves, and the inlet valves. Seven bearings support the camshaft. The camshaft is driven by an idler gear that is turned by the crankshaft in the front gear train. Each bearing journal is lubricated from the oil manifold in the cylinder block. A thrust pin that is located at the rear of the block positions the camshaft through a circumferential groove. The groove is machined at the rear of the camshaft. Timing of the camshaft is accomplished by aligning marks on the crankshaft gear, idler gear, and camshaft gear with each other.The injector lobe on the camshaft has a modified profile. The modified profile produces multiple injections. Vibration Damper
The force from combustion in the cylinders and from driveline components will cause the crankshaft to twist. This is called torsional vibration. If the vibration is too great, the crankshaft will be damaged. Driveline components can excite torsional stress. This stress will cause damage to components. The vibration damper limits the torsional vibrations to an acceptable amount in order to prevent damage to the crankshaft.The viscous vibration damper is installed on the front of the crankshaft. The viscous vibration damper has a weight in a case. The space between the weight and the case is filled with a viscous fluid. The weight moves in the case in order to limit the torsional vibration.