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. 14-21 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