Figure 5-24. Reaming Valve Guides

Figure 5-25. Refacing Valve Seat

available, proceed as outlined below:

Figure 5-24. Reaming Valve Guides

g. Obtain a scrap valve and grind three notches,

equally spaced, around the perimeter of the valve

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

face.

larger than original guide size (see Table 5).

h. Place valve in position against valve seat to be

5-32. VALVE SEAT REFACING

AND REPLACEMENT.

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

s e a t at each notch. Use an old head gasket to

a. If valve seats are not worn too badly they

protect head surface while welding, and exercise

may be refaced, using an electric tool with seat

care not to weld on cast head metal.

grinding attachment as shown in figure 5-25.

i. Use a rawhide hammer to drive out valve and

b . Be sure that the refacer grinding wheel is

old seat, as shown in figure 5-27.

properly dressed at the `correct angle and are the

proper wheels for the valve seat material (exhaust

valve seat inserts are Stellite No. 3).

j . Remove all burrs and foreign material from

counterbores.

c . Remove only enough stock to clean up pits

and grooves and to correct valve seat runout.

k. To insure squareness in entering and driving

the insert in the counterbore, it is important to

d. Exhaust valve seat inserts must be replaced if

seats are loose, pits and grooves too deep to be

provide a driving tool piloted in the valve guide.

removed, runout too excessive.

Such a tool is easily made up or adapted from the

valve guide installation tool by slipping a sturdy

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

washer-like driving plate somewhat larger than the

r e f a c e d to within specifications of Table 5, the

insert over the tool pilot.

seat will have to be driven out and replaced.

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

f. The preferred method of valve seat removal is

sufficiently

chilled.

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

5-23