TM 9-4910-679-14&P
MEASURING TAPPET CLEARANCE- (CONTINUED)
the block when depth gage is used. Turn engine until the tappet being gaged is at lowest point. With proper bushing and
beveled head fitted snugly in place, loosen knurled nut and slide stem (K) down to contact tappet. Clamp tightly in this
position with knurled nut. Remove the Depth Gage from engine and place in V-way of Attachment, with stem close to flat
grinding face of wheel. Clamp stem securely in place with quick-clamp (D). Adjust V-stop (E) to contact beveled head and
lock V-stop with knurled screw (H). Adjust Micrometer Feed Nut until stem just touches grinding face of wheel. Move
calibrated dial to O setting and the dial will move independently of the knurled nut at the end of the micrometer spindle. It
is now possible to grind definite clearances on the valve stem by turning the knurled nut. The dial will move with the
knurled nut and each calibration is 0.001". Do not grind end of Depth Gage.
GRINDING the VALVE STEM-
Swing the V-block Arm toward you, free of the wheel, and remove the
Depth Gage by loosening quick- clamp (D). Do not change setting of V-Stop (E).
Insert valve stem in V-way, with Valve head firmly seated in V-stop, and clamp in
position with quick-clamp. Turn back the Micrometer Feed Nut until valve stem
just clears grinding wheel. Start the wheel motor. Advance the micrometer feed
not more than 0.004"and rock the V-Block Arm slowly toward and across the flat
grinding face. Continue to rock back and forth until the wheel stops grinding;
swing the attachment toward you free of the wheel, advance the feed
another0.004"and again rock the attachment back and forth until the wheel stops
grinding. Repeat this operation, advancing the feed slowly until you reach the
reading noted above as the grinding limit. This will give you the correct tapped
clearance, and the valve stem end will be polished and squared.
It is important to dress the flat face of the grinding wheel frequently with the
diamond point, to ensure fast, clean grinding and a square valve stem-end If the
wheel is removed from spindle, it should be dressed again when replaced, to
ensure proper alinement.
As a final finishing touch to any job all valve stem ends should be squared
and polished--even on engines with adjustable tappets. This is easily and quickly
done on the Micrometer Attachment, using the V-way to position the valve stem,
but not using either the V-stop or the Micrometer Feed. A very light grind is
usually sufficient to square the stem.
SQUARING and TRUING TAPPETS-
Clamp tappets in the V-way of the attachment. Feed tappet up to contact the flat side of wheel. Swing attachment toward
you, free of wheel and start wheel motor. Advance micrometer feed only 0.002"or0.003"and swing back and forth across
flat face of wheel until the tappet end is square and polished. By using stop provided, tappets can be ground to the same
length if desired.
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