Yamaha MM700A, Manual, Page: 19 / 282

GENERAL INFORMATION 13
factured to close tolerances, and obtaining consistently
accurate measurements is essential to determining which
components require replacement or further service.
Each type of measuring instrument is designed to mea-
sure a dimension with a certain degree of accuracy and
within a certain range. When selecting the measuring tool,
make sure it is applicable to the task.
As with all tools, measuring tools provide the best re-
sults if cared for properly. Improper use can damage the
tool and result in inaccurate results. If any measurement is
questionable, verify the measurement using another tool.
A standard gauge is usually provided with measuring
tools to check accuracy and calibrate the tool if necessary.
Precision measurements can vary according to the ex-
perience of the person performing the procedure. Accu-
rate results are only possible if the mechanic possesses a
feel for using the tool. Heavy-handed use of measuring
tools produces less accurate results than if the tool is
grasped gently by the fingertips so the point at which the
tool contacts the object is easily felt. This feel for the
equipment produces more accurate measurements and re-
duces the risk of damaging the tool or component. Refer
to the following sections for specific measuring tools.
Feeler Gauge
The feeler or thickness gauge (Figure 24) is used for
measuring the distance between two surfaces.
A feeler gauge set consists of an assortment of steel
strips of graduated thickness. Each blade is marked with
its thickness. Blades can be of various lengths and angles
for different procedures.
A common use for a feeler gauge is to measure valve
clearance. Wire (round) type gauges are used to measure
spark plug gap.