ST valve adjustment.
Valve clearance both inlet and exhaust is 0.152mm. (0.006 in.) GO, 0.203mm. (0.008 in.) NOT GO. This is set
with the engine cold.
To adjust, remove the cylinder head cover and turn the piston to the T. D. C. position firing stroke, (both valves closed.)
Slacken the locknut on the adjusting screw and turn the screw until the correct clearance has been obtained. Tighten
the locknut whilst restraining the adjusting screw. and re-check to ensure that the clearance is correct.
A word of caution - after adjusting the valves it might be wise to check for decompressor adjustment.
ST decompressor adjustment.
For engines provided with an oil filter hole in each cylinder head cover, access to the decompressors is through these holes.
Turn the piston to T. D. C., firing stroke.
Move the decompressor lever over towards the flywheel.
Slacken the locknut and turn the decompressor screw down until the exhaust valve touches the piston.
Turn the screw back 1/2 turn and tighten the locknut.
When no filler is provided in the cylinder head cover the decompressor should be adjusted so that when the cover is
tightened down in position, the adjusting screw just touches the valve rocker when operated. The adjusting screw should
then be screwed down 3/4 turn and locked in position.
This information is from the Lister book 1705 for ST and STMA diesel engines, operators handbook.