Lesson 3 Measurement

Tools used in measuring engine components Micrometer caliper – precision measuring tool for taking outside measurements. Inside micrometer – determines the inside of a cylinder Flat feeler gage – recognizes the spacing between two surfaces Dial indicator – recognizes the spacing between two surfaces and records readings of the dial needle

Tools (continued) Round-wire gage – used in measuring the electrode gap of spark plugs Plastigage – a thin, plastic, threadlike material used to measure the clearance between the bearing journal on a crankshaft and the bearing rod cap

Plastigage

Tools (continued ) Torque wrench – the hand tool used for torque which bolts and nuts must be tightened to Compression gage – helps in determining if there is a problem with the cylinder, piston rings, valves, or gaskets. It measures compression pressure in pounds per square foot

Compression Gage

Tools (continued) Telescoping gage – a tool used for measuring inside diameter Tachometers – used for reading revolutions per minute

Telescoping Gage

Specifications of an internal combustion engine Charts detail the exact specification to increase performance and prolong life Related to engine size and work requirements Clearances of the intake and exhaust valves

Four major specifications on small engines Fuel Oxygen Compression Ignition

Fuel Use the fuel recommended by the manufacturer Guidelines for carburetor adjustments: Turning valve clockwise creates leaner fuel mixture Turning valve counter clockwise creates richer fuel mixture

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

Compression Not having compression indicates a serious problem in the engine Quick test method: pull the starter rope. If there is no resistance against the starter rope, the engine lacks compression

Ignition Routinely check spark plugs Clean the electrodes with a wire brush If reinstalling spark plugs, the plug gap should be adjusted properly

Setting the gap on a spark plug

Reading the Micrometer

This is a English micrometer thimble sleeve anvil spindle frame

Let’s take a close look at the sleeve of the micrometer.

/10 inch (0.100) 25/1000 inch (0.025) 1/1000 inch (0.001) One inch (1.000)

Now, an example...

Smallest Measurement Largest sleeve reading Now, an example... One mark past largest sleeve reading Thimble Reading inches

A digital micrometer

Another example...

Smallest Measurement Largest sleeve reading Three marks past largest sleeve reading Thimble Reading inches Another example...

Least Precise Accuracy of 1/16” (.0625”) Used on large items and “non-precision” work Available in various lengths

Divided into increments of 1/16” (standard) * sometimes smaller Metric on the opposite side Bold numbers indicate inches

Accuracy of.001” 0” – 6”, 0” – 12”, 0” – 36” Used on precision jobs Measures Outside Diameters, Inside Diameters, And Depths

Each increment on the bar represents.100” Each round on the dial equals.100” or.200” Depending on the brand of the tool Bold numbers on the dial represent.010” Small dashes equal.001”

English Linear Units 12 inches (in.) = 1 foot (ft.) 3 ft. = 1 yard (yd.) 5280 ft. = 1 mile 1720 yd. = 1 mile

English Area Units 144 square inches (sq. in.) = 1 square foot (sq. ft.) 9 sq. ft. = 1 square yard (sq. yd.) 43,560 sq. ft. = 1 A 640 A = 1square mile (sq. mi.)

English Volume Units Liquid Measurements 1 pint (pt.) = 16 ounces (oz.) 2 pt. = 1 quart (qt.) 4 qt. = 1 gallon (gal.) 7.48 gal. = 1 cubic foot (cu. ft.)

English Weight Units 16 oz. = 1 lb. 100 lb.= 1 hundredweight (cwt.) 2,000 lb. = 1 ton (T) 2,240 lb. = 1 long ton

Figuring Area of Objects

Determining the Area of a Rectangle If width = 1,000 ft length = 2,000 ft 1,000 x 2000 ft = 20,000 ft 2

Determining the Area of a Triangle

If base = 600 ft. and height = 750 ft. area = 600 x area = 210,000 ft 2 area = 4.82 acres

Determining the Area of a Circle

Volume 3 Dimensional in “cubic” units Important to remember - when converting from cubic feet to cubic yard, divide by 27

Determining Cubic Area

Length = 100 ft Width = 20 ft Height = 20 ft Volume = 40,000 ft 3

Determining the Volume of a Cylinder

If height = 10 feet and radius is 3 feet what is the volume of this cylinder? 3 2 x 3.14 x 10 = ft 3