Cub Cadet MTD 70 Series - Manual (Page 113)

Cylinder head
107
6. Inspect the valve seat. See Figure 9.10.
• Valve seats are 45 degrees, with a 15 degree top-
ping cut and a 75 degree narrowing cut.
• Seat width should be 0.043” - 0.050” (1.1 - 1.3 mm)
with a margin of 0.024” (0.6mm) on the exhaust
valve and 0.027” (0.7 mm) on the intake valve.
NOTE: The valve seat can be ground to clean it up as long
as the finished seat is within the tolerances listed
above.
7. Inspect the valve stem. See Figure 9.11.
8. Inspect the valve springs.
NOTE: Valve spring free length should be at least 1.22”
(28.5mm). Original length is 1.44” (36.6 mm).
9. Install the valves in the cylinder head by following
steps 2 - 5 in reverse order.
10. Test the valves for leaks by:
10a. Place the cylinder head on a couple of wood
blocks with the valves facing up.
10b. Pour a small amount of gasoline or parts clean-
ing solvent into the combustion chamber (just
enough to cover the valves).
10c. Let the cylinder head sit for ten minutes.
10d. Check for gasoline leaking out of the intake and
exhaust ports.
11. Install the cylinder head by following the steps
described earlier in this chapter.
12. Set the valve lash by following the steps described in
Chapter 1: Introduction.
13. Test run the engine in a safe area before returning it
to service.
Figure 9.10
Seat angle is 45
o
.043-.050”
Figure 9.11
45
o
Inspect for a
burnt edge