5031139 JOHNSON CUSHION, Injector

Cylinder Block
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Cylinder block
The cylinder block is made of cast iron with an integral crankcase. The sides of the cylinder block extend below the center line of the crankshaft in order to provide added strength. The cylinder block provides full support for the length of the cylinder bores.All of the bores are honed with silicon carbide tools to a controlled finish in order to ensure long life and low oil consumption.The cylinder block has a front camshaft bearing that is installed for the front camshaft journal. The other camshaft journals run directly in the cylinder block.Cylinder Head
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Cylinder head
The cast iron cylinder head is fastened to the cylinder block by ten flanged bolts. The cylinder head gasket has a soft outer surface with an inner steel core. The inlet and exhaust ports are designed to improve air flow.The cylinder head assembly has two overhead valves for each cylinder. Each valve is held in place by a single coil spring, a cap, and two collets. The cylinder head has steel valve seat inserts for both the inlet and exhaust valves. The valves move in steel valve guides. Each valve guide is equipped with a synthetic rubber oil seal. The exhaust valve guides have a counterbore in order to prevent seizure of the valve stem that is caused by a buildup of carbon underneath the head of the valve. Both the valve seat inserts and the valve guides can be renewed.The overhead valves are operated by a rocker shaft assembly that is installed under a composite valve mechanism cover. The forged steel rocker arms are operated by cold drawn pushrods with hardened heads. The rocker shaft is supported by steel brackets that support the rocker shaft between each pair of valves. The rocker shaft assembly and valve components are lubricated by an oil flow from the hollow rocker shaft. The rocker shaft receives a reduced oil flow from the oil feed of the camshaft.Valve lash is adjusted by adjustment screws and locknuts at the pushrod end of each rocker arm.The inlet manifold and the water temperature regulator housing are integral within the cylinder head. The valve mechanism cover also contains the crankcase breather and breather pipe.Pistons
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Piston
The pistons have a FASTRAM combustion chamber in the top of the piston. The piston crater ensures an efficient mix of fuel and air.The pistons have two compression rings and an oil control ring. The groove for the top ring has a hard metal insert that reduces wear of the groove. The piston skirt has a layer of graphite in order to improve the wear characteristics. The fully floating piston pin is held in an axial location by circlips. The piston pin is placed off-center in order to reduce the noise level.The piston cooling jets spray lubricating oil onto the inner surface of the piston in order to cool the piston.The piston height is adjustable. The correct piston height is important in order to ensure that the piston does not contact the cylinder head and that the fuel has efficient combustion.Connecting Rods
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Connecting rod
The pistons and the connecting rods are matched to each cylinder. The piston height is controlled by the length of the connecting rods. The piston pin bearing in the connecting rod is machined off-center in order to obtain the different length grades. There are six different length grades of connecting rods that are used in order to obtain the correct piston height.
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Fracture split end of the connecting rod
The connecting rod is a one-piece forging that is fractured hydraulically in order to split the big end cap from the connecting rod. This process produces a rough surface that is accurately matched on each side for improved strength. The rough surface also prevents lateral movement of the mating surfaces.Crankshaft
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Crankshaft
The crankshaft is forged from chrome molybdenum steel. The crankshaft has five main journals. The flywheel is attached to the large flange at the rear of the crankshaft.End play of the crankshaft is controlled by two split 360° thrust washers that are located on both sides of the center main bearing.The main bearings have steel backs with an aluminum and tin bearing material. The main bearing caps are made of cast iron or spheroidal graphite (SG) iron.The one-piece rear oil seal is made from a PTFE material. The crankshaft pulley is held in position by a plain thrust block and three bolts.
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Timing wheel
The timing wheel is an interference fit onto a machined surface of the crankshaft web. The timing wheel is located by a dowel (2) that is behind the rear flange of the crankshaft. The timing wheel has space for 36 teeth with one missing tooth (1) that is located 70 degrees after top center.Camshaft
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Camshaft
The engine has a single camsha