LessonLesson

Measuring Engine Measuring Engine Components and Components and

SpecificationsSpecifications

Interest ApproachInterest ApproachHow are internal combustion engine How are internal combustion engine

specifications determined?specifications determined?

Student Learning ObjectivesStudent Learning Objectives

Identify measuring and testing Identify measuring and testing equipment for internal combustion equipment for internal combustion enginesengines

Identify the specifications of an Identify the specifications of an internal combustion engineinternal combustion engine

Explain four major specifications to Explain four major specifications to be checked on small engines.be checked on small engines.

TermsTerms

Compression Compression gagegage

Dial indicatorDial indicator Flat feeler gageFlat feeler gage Inside micrometer Inside micrometer

setset Micrometer Micrometer

calipercaliper

PlastigagePlastigage Round-wire gageRound-wire gage TachometersTachometers Telescoping gageTelescoping gage Torque wrenchTorque wrench

Tools Used in Measuring Engine Tools Used in Measuring Engine ComponentsComponents

Micrometer caliper – precision Micrometer caliper – precision measuring tool for taking outside measuring tool for taking outside measurements. measurements.

Inside micrometer – determines the Inside micrometer – determines the inside of a cylinder.inside of a cylinder.

Tools Used in Measuring Engine Tools Used in Measuring Engine ComponentsComponents

Flat feeler gage – recognizes the Flat feeler gage – recognizes the spacing between two surfaces.spacing between two surfaces.

Dial indicator – recognizes the Dial indicator – recognizes the spacing between two surfaces and spacing between two surfaces and records readings of the dial needle.records readings of the dial needle.

Tools (continued)Tools (continued)

Round-wire gage – used in Round-wire gage – used in measuring the electrode gap of measuring the electrode gap of spark plugs.spark plugs.

Plastigage – a thin, plastic, Plastigage – a thin, plastic, threadlike material used to measure threadlike material used to measure the clearance between the bearing the clearance between the bearing journal on a crankshaft and the journal on a crankshaft and the bearing rod cap.bearing rod cap.

PlastigagePlastigage

Tools (continued)Tools (continued)Torque wrench – the hand tool Torque wrench – the hand tool

used for torque which bolts and used for torque which bolts and nuts must be tightened to.nuts must be tightened to.

Compression gage – helps in Compression gage – helps in determining if there is a problem determining if there is a problem with the cylinder, piston rings, with the cylinder, piston rings, valves, or gaskets. valves, or gaskets. • It measures compression pressure It measures compression pressure

in pounds per square foot.in pounds per square foot.

CompressionCompressionGageGage

Tools (continued)Tools (continued)

Telescoping gage – a tool used for Telescoping gage – a tool used for measuring inside diameter.measuring inside diameter.

Tachometers – used for reading Tachometers – used for reading revolutions per minute.revolutions per minute.

Telescoping GageTelescoping Gage

Specifications of an internal Specifications of an internal combustion enginecombustion engine

Charts detail the exact specification Charts detail the exact specification to increase performance and to increase performance and prolong life.prolong life.• Related to engine size and work Related to engine size and work

requirements.requirements.

• Clearances of the intake and exhaust Clearances of the intake and exhaust valves .valves .

Four major specifications on Four major specifications on small enginessmall engines

FuelFuelOxygenOxygenCompressionCompression IgnitionIgnition

FuelFuel

Use the fuel recommended by the Use the fuel recommended by the manufacturer.manufacturer.

Guidelines for carburetor Guidelines for carburetor adjustments:adjustments:• Turning valve clockwise creates Turning valve clockwise creates

leaner fuel mixture.leaner fuel mixture.

• Turning valve counter clockwise Turning valve counter clockwise creates richer fuel mixture.creates richer fuel mixture.

OxygenOxygen

Engines need to take in clean air in Engines need to take in clean air in order for combustion to occur.order for combustion to occur.• Air filters should be routinely checked Air filters should be routinely checked

and cleaned.and cleaned.

CompressionCompression

Not having compression indicates a Not having compression indicates a serious problem in the engine.serious problem in the engine.

Quick test method: pull the starter Quick test method: pull the starter rope. rope.

If there is no resistance against the If there is no resistance against the starter rope, the engine lacks starter rope, the engine lacks compression.compression.

IgnitionIgnition

Routinely check spark plugs.Routinely check spark plugs.Clean the electrodes with a wire Clean the electrodes with a wire

brush.brush. If reinstalling spark plugs, the plug If reinstalling spark plugs, the plug

gap should be adjusted properly.gap should be adjusted properly.

Setting the gap on a spark plug

Review / SummaryReview / Summary

What are some of the instruments What are some of the instruments used for measuring internal used for measuring internal combustion engines?combustion engines?

What are the specifications of an What are the specifications of an internal combustion engine?internal combustion engine?

What are four major specifications What are four major specifications that are commonly checked on that are commonly checked on small engines?small engines?