Yard Machines Y60 Operations Instructions download pdf (Page 185)

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Figure 5-24. Reaming Valve Guides

e. Do not over-ream valve guides. Use ream no

larger than original guide size (see Table 5).

5-32. VALVE SEAT REFACING

AND REPLACEMENT.

a. If valve seats are not worn too badly they

may be refaced, using an electric tool with seat

grinding attachment as shown in figure 5-25.

b. Be sure that the refacer grinding wheel is

properly dressed at the ‘correct angle and are the

proper wheels for the valve seat material (exhaust

valve seat inserts are Stellite No. 3).

c. Remove only enough stock to clean up pits

and grooves and to correct valve seat runout.

d. Exhaust valve seat inserts must be replaced if

seats are loose, pits and grooves too deep to be

removed, runout too excessive.

e. If seat is worn so badly that it cannot be

refaced to within specifications of Table 5, the

seat will have to be driven out and replaced.

f. The preferred method of valve seat removal is

to use a valve seat insert puller. If a puller is not

Figure 5-25. Refacing Valve Seat

available, proceed as outlined below:

g. Obtain a scrap valve and grind three notches,

equally spaced, around the perimeter of the valve

face.

h. Place valve in position against valve seat to be

removed, as shown in figure 5-26, and tack weld to

seat at each notch. Use an old head gasket to

protect head surface while welding, and exercise

care not to weld on cast head metal.

i. Use a rawhide hammer to drive out valve and

old seat, as shown in figure 5-27.

j. Remove all burrs and foreign material from

counterbores.

k. To insure squareness in entering and driving

the insert in the counterbore, it is important to

provide a driving tool piloted in the valve guide.

Such a tool is easily made up or adapted from the

valve guide installation tool by slipping a sturdy

washer-like driving plate somewhat larger than the

insert over the tool pilot.

l. Shrink the valve seat by placing in dry ice until

sufficiently chilled.

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Yard Machines Y60 Operations Instructions Page 185

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