Cub Cadet MTD 70 Series - Manual (Page 21)

Introduction
15
75 series engines
6. Check valve lash between each valve stem and
rocker arm using a feeler gauge.
6a. Intake valve lash should be 0.004” - 0.006”
(0.10 - 0.15 mm). See Figure 1.16.
6b. Exhaust valve lash should be 0.006” - 0.008”
(0.15 - 0.20 mm). See Figure 1.17.
6c. Use a 10mm wrench to loosen the jam nut.
Adjust the jack screw using a small flat headed
screw driver.
• Tighten the jack screw to close-up the clearance
between the end of the valve stem and the contact
point on the rocker arm.
• Loosen the jack screw to open-up the clearance
between the end of the valve stem and the contact
point on the rocker arm.
7. Rotate the engine through several compression cycles:
• Observe the movement of the valve gear.
• Return the piston to TDC compression stroke and re-check the valve lash to confirm consistent movement
of the valve gear, including the slight bump to the exhaust valve from the automatic compression release.
8. Clean-up any oil around the valve cover opening, clean the valve cover, replace the valve cover gasket if nec-
essary.
9. Install the valve cover, tightening the valve cover screws to a torque of 62 - 80 in-lbs (7 - 9 Nm).
IMPORTANT: Over tightening the valve cover will cause it to leak.
10. Install the spark plug.
11. Test run the engine before returning it to service.
Figure 1.16
Feeler gauge
Figure 1.17
Feeler gauge