TM 9-4910-679-14&P
VALVE SEAT GRINDING OPERATIONS
CAUTION: Always wear eye protection.
CARBON CLEANING-Use a 1/4" Drill for driving wire carbon cleaning brushes in
removing carbon from the engine block and cylinder heads. The bright,
burnished surface produced will retard carbon accumulation in the completed job.
Kerosene will help to remove very hard carbon. Use proper brushes on
aluminum heads to avoid scoring. After carbon cleaning thoroughly remove all
loose carbon dust.
To sharpen carbon brushes, grind the wire ends square by holding the brush in
an electric drill with the brush revolving against a running grinding wheel.
Valve guides require very careful cleaning. Carbon left' in the
guide will deflect the pilot, resulting in inaccurate work. With '4"
drill, and correct size cleaner, use the following procedure. 1.
Insert cleaner in guide before starting drill. 2. For better cleaning,
move cleaner up and down in guide several times--be sure portion
of bristles is kept within the valves guides. 3. Wipe bristles with
clean cloth after cleaning each guide. 4. The bristles will not be
adversely affected by oil or gasoline.
INSERTING THE PILOT- After the proper size pilot for the valve guide has been selected, the tapered sleeve on this pilot
should be run out on its thread as far as possible. Then insert this pilot until its upper taper stops on the top of the valve
guide. Turn the pilot clockwise with a pilot pin or pilot wrench to draw the split sleeve against the pilot's lower taper, thus
expanding the split sleeve and locking the pilot tightly in the guide. Do not overtighten--a firm fit is desirable; To remove
the pilot, turn it once or twice counterclockwise and pull out.
INSTALLING STONE and SLEEVE on PILOT-
Apply thin film of oil to the pilot--slide the stone sleeve down on the pilot shank until the stone rests on the valve seat.
Use two stone sleeves to facilitate seat grinding. One sleeve may carry a
Reconditioning Valve Seat
Grinding stone, another a 15 narrowing stone. This procedure eliminates the delay involved in changing stones on one
sleeve for once the pilot is placed in a valve guide both the finishing and narrowing cuts are usually made to complete that
particular valve seat before removing the pilot.
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