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ENGINE CONSTRUCTION

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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.

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Engine Bottom End

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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

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Cylinder Block

Common cylinder configurations:

Vee, inline, opposedAnd slant.Number from

farthest front backwards

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Crankshaft Converts

reciprocating motion into rotary motion.

Made of either nodular iron, forged steel, or billet steel.

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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

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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.

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Crankshaft Service Grinding Cranks Undersize bearings

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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.

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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.

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Balancer Shafts Used to counteract

the normal vibrations inherent to piston engines.

Found on 4 cylinder and 6 cylinder engines mostly.

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Covers & Pans Made of steel

metal, aluminum, or plastic materials.

Usually use gaskets or seals.

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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.

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Pistons

Pistons harnessthe energy ofthe power strokeand transfers the force towardthe crankshaft.

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Piston Terminology Head or crown Ring grooves Ring lands Oil return holes Skirt Pin hole Pin boss Pin offset

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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.

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Piston Ring Wear Causes a loss of

compression. Causes excessive

oil consumption. May cause blue smoke out the tail pipe.

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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.

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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.

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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.

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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

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Rods MUST match caps

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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

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Free and Non-Free running Engines 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.

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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.

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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.

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Cylinder Bore Wear Wears oval

shaped. Cylinder wall

tapers. Pocket forms near

the top. A ridge forms at

the top.

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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”

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Crankshaft Wear Wears out of round

due to the power strokes.

Grinding can restore the journals, however they are smaller requiring under sized bearings.