Valve Springs; Rocker Arm And Rocker Shaft Service - Toro Groundsmaster 300 Series Service Manual

Valve Springs (Fig. 59)
1. Check the valve springs for rust, pitting, cracks or
other damage.
2. Check the squareness of the valve spring by placing
it upright on a level surface. Springs may be out of
square by 1.5 degrees. Springs that are out of square
by 3 degrees or more must be replaced.
3. Measure the spring free length. The standard dimen-
sion is 1.69 inches (43 mm). Springs which measure
1.64 inches (41.7 mm) or shorter must be replaced.
4. Over time, valve springs can lose some of their
tension. Test the springs to make sure that the spring
pressure is within the following limits: 23.5 - 28.5 lbs.
(11.2 - 12.4 Kg) with the installed length of 1.46 inches
(37.1 mm). When the spring pressure at the length given
is 20 lbs. (9.5 Kg) or less, the spring must be replaced.
NOTE: Valve springs are inexpensive compared to the
cost of repairing engine damage due to weak valve
springs.
Rocker Arm and Rocker Shaft Service (Fig. 60)
1. Disassemble the rocker shaft by removing the outside
retaining rings on each end and by removing the two
rocker arms stay bolts and seats from the rocker shaft.
2. Inspect each rocker arm for signs of wear where they
contact the valve tip and push rod contact surfaces.
Rocker arms which are worn should be replaced.
3. Examine the rocker shaft for excessive wear or
damage. Replace it if it is defective.
4. Measure the rocker arm inside diameter and the shaft
outside diameter. The maximum clearance between the
rocker arm and the rocker arm shaft should be .0079
inches (0.2 mm). Replace the shaft if clearance is in
excess of this dimension.
5. Inspect the oil passages in the rocker shaft and rocker
arms to make sure that they are clear of obstruction.
Clean if necessary.
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Groundsmaster 300 Series
Checking valve spring length
Page 4 - 51
Figure 59
Figure 60
Rocker arm and shaft
Cylinder Head Overhaul