Engine Measuring

Vernier (Dial) Caliper Useful because it can read inside and outside measurements. Use only as a “rough” guide. Add the reading on the blade to the reading on the dial.

Micrometer The most used measuring instrument in engine service and repair  Each revolution of the thimble moves the spindle.025”.  The thimble is graduated into 25 equally spaced lines so ….  Each line represents.001”

Crankshaft Measurement Measure for out-of-round  Measure the journal in at least six different positions across the diameter at 60 degree increments. This should be done at the same horizontal position.  Subtract the highest from the lowest to factor out- of-round.

Crankshaft Measurement Crankshaft taper – measure the journal at two different horizontal positions across the journal and subtract to factor taper.

Telescopic Gauge Used in conjunction with a micrometer to determine the inside diameter of a hole. The gauge is inserted until contact is present and then locked. A micrometer is then used for measurement.  Use only if necessitated.

Small (split)-ball Gauge Similar to a telescopic gauge in that it is used in conjunction with a micrometer to determine the inside diameter of a hole.

Small (split)-ball Gauge The gauge is inserted until contact is present and then locked. A micrometer is then used for measurement. Used for small bores.  example: valve guide

Split-ball Probe More accurate than a split ball gauge  Often used for larger bores

Feeler Gauge An accurately manufactured strip of metal used to factor the gap or clearance between two components.  Used for: Piston ring gap Piston ring side clearance Connecting rod side clearance Warpage

Straightedge A precision ground metal used to check to flatness of a component. Used for: Cylinder heads Block deck

Dial Indicator Measures variations from zero  Used to check Runout Crankshaft endplay Valve guide wear

Dial Bore Gauge The most accurate way to measure bore diameter, taper or out- of-round. Gauge must be “set-up” and zeroed before usage.  Used for: Cylinders Main bores Connecting rod bores Bearing bores