Vanguard BIG BLOCK M540000, Руководство по ремонту, Страница: 94 / 168

H. Remove valve from the cylinder head and thoroughly
clean the valve face and valve seat of any lapping
compound. Use a clean rag dipped in mineral spirits
for good results.
I. Carefully inspect the seating surface on the valve
face ( C ). A properly lapped valve shows a gray,
frosty seating surface located near the center of the
valve face. Verify that the lapped surface extends
evenly and completely around the entire valve face
with a contact area 0.047-0.063 inches (1.19-1.59
mm) wide.
Carefully inspect the seating surface on the valve
seat. The valve seat should also show an unbroken
lapped finish of uniform width.
9. If the desired results are not observed, obtain a valve
seat cutting tool kit. For engines equipped with 3-angle
valve seats, see Figure 112, and proceed as follows. For
engines equipped with single-angle valve seats, go to
step 11.
NOTE: Carefully read manufacturer's directions for proper
assembly and use of valve seat cutting tool.
A. Install the proper sized pilot in the intake valve guide.
NOTE: Do not drop the cutter onto the valve seat during
installation or removal, as the blades may cause seat damage
that requires additional cutting.
NOTE: Applying too much pressure or rotating the cutter too
fast will produce chatter marks that adversely affect sealing
integrity. Rotate the cutter slowly, so that it takes about three
seconds to make one complete rotation.
112
B. Install the 60° cutter on the pilot to make the bottom-
narrowing cut. Rotate the cutter three of four turns,
so that it cuts all the way around the valve seat.
C. Install the 30° cutter to make the top-narrowing cut.
D. Install the 45° base angle cutter and cut the seat
contact area until it is approximately 0.047-0.063
inches (1.19-1.59 mm) wide.
E. Use low pressure compressed air to thoroughly
remove all cutting chips and metal shavings.
Remove pilot from valve guide.
F. Lap the valve face and seat a second time to verify
location and width of the seat contact area.
G. If the seat contact area is too narrow, recut using the
45° base angle cutter.
H. If the seat contact area is too wide, repeat steps 9(B)
and 9(C).
10. Perform steps 8-9 on the exhaust valve.
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