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ENGINE CONSTRUCTION. Engine Block Assembly. Very sophisticated casting. Made of cast iron or aluminum with cast iron cylinder liners. A great deal of machining involved in the process of manufacturing. Becomes the frame of the engine. Engine Bottom End. Bottom End Parts. Block Crankshaft
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Engine Block Assembly • Very sophisticated casting. • Made of cast iron or aluminum with cast iron cylinder liners. • A great deal of machining involved in the process of manufacturing. • Becomes the frame of the engine.
Bottom End Parts • Block • Crankshaft • Connecting Rod • Pistons, Rings, & Wrist Pin • Bearings (Main and Connecting rod) • Caps (main and Connecting Rod) • Fly Wheel and nuts and bolts
Cylinder Block Common cylinder configurations: Vee, inline, opposed And slant. Number from farthest front backwards
Crankshaft • Converts reciprocating motion into rotary motion. • Made of either nodular iron, forged steel, or billet steel.
Crankshaft Terminology • Crankpins or throws • Main bearing journals • Rod bearing journals • Thrust bearing • Main caps • Oil passages • Flywheel flange • Vibration damper end • Keyway • Rear main seal • Front crankshaft seal • Counter weights • Firing order
Crankshaft Bearings • Known as friction or precision insert bearings. • Uses a steel backing with soft metal on crankshaft side.(lead,tin, copper, silver, cadmium) • Oil clearance between crankpin and bearing very critical. (.001”) • Oil Clearance measured with plastigauge.
Crankshaft Service • Grinding Cranks • Undersize bearings
Flywheel • The flywheel (known as the flex plate when used with an automatic transmission) carries the engines inertia in between power strokes. • It is the power take off for the engine. The clutch or torque converter bolts to it. • Lastly it has the starter motor’s ring gear.
Vibration Damper • The vibration damper smoothes the vibrations caused by the power strokes. • It has a pulley on it the run auxiliary systems. • It may contain timing marks or crankshaft timing sensors.
Balancer Shafts • Used to counteract the normal vibrations inherent to piston engines. • Found on 4 cylinder and 6 cylinder engines mostly.
Covers & Pans • Made of steel metal, aluminum, or plastic materials. • Usually use gaskets or seals.
Gaskets, Seals and Sealers • Gaskets seal two stationary surfaces. • Seals do it when one surface moves. • Many types of materials: rubber, paper, aluminum, steel, cork and more. • Sealers adhere gaskets to one of the surfaces.
Pistons Pistons harness the energy of the power stroke and transfers the force toward the crankshaft.
Piston Terminology • Head or crown • Ring grooves • Ring lands • Oil return holes • Skirt • Pin hole • Pin boss • Pin offset
Piston Rings • Rings seal the compression in the combustion chamber and the motor oil in the crankcase. • Automotive engines use 3 rings: 2 compression and 1 multi-piece oil ring.
Piston Ring Wear • Causes a loss of compression. • Causes excessive oil consumption. May cause blue smoke out the tail pipe.
Types of Piston Rings • Rings are usually made of cast iron • can be plated with chrome or molybdenum. • Help seal the ring to the cylinder wall. • Shapes of the ring vary to also help the ring seal better.
Piston Pin (Wrist Pin) • Hollow polished steel pin. • Attached in a variety of ways. • Pinned to piston. • Clamped to rod small end. • Snap ring free floating. • Press fit.
Connecting Rods • I-beam style rod use to transfer the pistons force to the crankshaft. • Small end contains the piston pin and the big end has a removable cap to install it to the Crank. • Nuts and bolts are usually of a very high quality.
Installation of Pistons • Cylinder number • Piston number • Notch to the front • Position ring gaps • Remove rod cap check bearing inserts • Cover bolts with fuel line if needed • Crankshaft at TDC or BDC • Install ring compressor • Oil piston, cylinder wall, & crank journal • Carefully tap in piston with hammer handle. • Properly replace rod cap
Weird Science of Engines • Free running and Non-free running • Crankshaft rotation versus piston travel • Piston side thrust • Piston pin offset • Cylinder bore wear • Crankshaft journal wear
Free running engines can have their piston at TDC and their valves wide open and the valve won’t touch the piston. Non-free running engines will crash the valves into the piston if the piston is at TDC and the valves are wide open. This will wreck the engine. Free and Non-Free running Engines
Piston Travel Verses Crankshaft Rotation • When the piston move ½ way down the bore the crankshaft does not turn a ½ a turn. This will always create vibration.
Piston Side Thrust • There are two sides to the piston. • The thrust side and the relief side. • Wear occurs mainly on the thrust sides. • Skirt area is not even needed on the relief side. • Piston pin offset counteracts side thrust.
Cylinder Bore Wear • Wears oval shaped. • Cylinder wall tapers. • Pocket forms near the top. • A ridge forms at the top.
Cylinder Boring • Cylinders can be bored to restore them however they will be larger requiring bigger pistons. • Usually bored to .010”, .020”, .030”, or .050”
Crankshaft Wear • Wears out of round due to the power strokes. • Grinding can restore the journals, however they are smaller requiring under sized bearings.