Engine Components and Cylinder Numbering

Cylinder Numbering

• Lycoming 4-cylinder engine: C, D, 1, 3, A, 4, B, 2
• Continental 4-cylinder engine: C, D, 1, 3, A2, B4,
• Lycoming 6-cylinder engine: C6, B4, A2, F5, E3,
• Continental 6-cylinder engine: D, 1, 3E, 5F, 2A, 4, B6, C

Major Engine Components

• Crankcase: A component of the engine that contains the cylinders (image shown in purple)
• Valve: Mechanical component that opens and closes to allow flow of gases.
• Connecting rod: Connects the piston to the crankshaft
• Camshaft: Used to coordinate valve opening and closing
• Piston: Moves up and down inside the cylinder
• Piston pin: Connects the piston to the connecting rod
• Cylinder: The part of the engine containing the piston.
• Compression ring: Rings that seal the cylinder walls to prevent leakage.

Piston Rings

• Concave: A type of piston head
• Truncated cone: A type of piston head
• Domed: A type of piston head
• Flat: A type of piston head
• Oil control ring: A ring that controls the flow of oil
• Piston rings: A set of rings that seal the cylinder walls, shown in the image.

Types of Bearings

• Axial & radial: A type of bearing
• Roller / Radial: A type of bearing
• Recessed: A type of bearing

Lubrication

• Increasing engine volumetric efficiency
• Reducing friction
• Increasing engine compression ratio
• Reducing engine maximum speed
• Absorbing heat (reducing engine temperatures)
• Cushioning engine parts
• Decreasing engine compression ratio
• Improving engine mid-range torque
• Increasing engine frictional losses
• Increasing flight control rate of motion
• Cleaning (cleaning/removing debris)
• Protecting from corrosion;
• Improving planned obsolescence
• Accelerating wear and corrosion

Cooling (1)

• Trapping air above/below engine raises pressure
• Directing the air through engine's cooling system

Cooling (2)

• High performance piston aircraft: thermostat, wing flaps, and cowl flaps control engine temperature.
• Engine cowl: directs air around the engine for cooling.
• Cowl flaps control the amount of air leaving the cowls.

Cooling (3)

• Engine uses a single CHT probe in a specific hot cylinder
• Horizontal opposed aircraft use oil cooling via cooling fins on cylinder assemblies

Cooling (4)

• Instruments for air-cooled engines: CHT (cylinder head temperature), EGT (exhaust gas temperature).
• Air-cooled engines use liquid cooling systems or air cooling systems
• Liquid Cooling systems are preferred for higher-performance engines.
• Components of a liquid cooling system: Reservoir, radiator, thermostat, and water jackets
• Percentage of engine cooling from oil is a small amount like 40%

Oil Temperature

• Component that controls oil temperature: oil cooler
• Component that reduces oil temperature: oil cooler
• Mil-L-22851D: ashless dispersant oil used during the break-in period or during hot weather
• Mil-L-60823E: straight mineral oil used after break-in period

Suction Screens

• Purpose: preventing large particles from damaging the pump
• Location: after the oil pump and before the pressure relief valve or filter

Carb Parts

• Brass float, Composite float, Plastic float, Boost venturi, Main venturi, Discharge nozzle, Drain plug, Idle mixture screw, Throttle valve, Pump discharge tube, Mixture control, Accelerator pump, Needle valve, Float.

Engine Control (15)

• Throttle valve controls air flow
• Mixture control: a system relating the mixture of fuel and air in combustion.

Mixture Ratio

• Mixture ratio: proportion of fuel to air.
• Rich mixture: high fuel-to-air ratio
• Lean Mixture: Low fuel-to-air ratio.

Idling Systems

• Idle Mixture port: a port located just down stream or above the throttle valve.

Carb Adjustments (21)

• Idle speed adjustment: turning the adjustment screw; cold conditions for cold engine adjustment.
• Idle adjustment to raise speed: clockwise for hot condition
• Idle adjustment to lower speed: counterclockwise when cold.
• Float level adjustment: bending the needle valve tab.