A.J.S. 16, Instruction Book

Page: 29 / 104

The tappet rods are made of Light Alloy, and in manufacture, the sleeve marked 5 in
illustration 11 is fitted to the bare rod and then the push sleeve and the rod are threaded
to take the adjusting screw marked 3.
It will consequently be seen that, contrary to the practice when steel rods are used, it
is not possible to supply and fit sleeve 5 to an existing light alloy rod.
Consequently the "Push Rod, bare" will only be supplied for spares purposes complete
with sleeve 5 already fitted and threaded.
TO ADJUST OVERHEAD ROCKERS (Tappet Clearance)—TWINS
Using key bar 018055 remove screws securing a rocker cover. (It is desirable to deal
only with one cover at a time.)
Lift off the cover, exposing the rocker.
Using single-ended spanner 015264, slightly slack off the nut of the bolt clamping the
disc headed end of the rocker spindle. (See note below.)
Then slowly revolve the engine, by means of the kick-starter pedal, till well past the
position at which the valve closes and then proceed to revolve the rocker spindle until
the correct clearance is obtained, whereupon, re-tighten the locking nut and replace
the cover. (Inspect gasket under rocker cover and, if damaged, replace with new.)
The correct rocker clearance, with cold engine, is ·008" for both inlet and exhaust.
It is best to ensure that each piston, in turn, is at the top of its firing stroke when adjusting
rocker clearances. The method of obtaining that position is explained in the paragraph
dealing with
Timing the Ignition. This piston position is essential to ensure the
cam levers are well clear of the cam quietening curves when adjusting rocker clearance.
It should, perhaps, be explained here that these quietening curves, as they are called,
are actually slight inclines from the base circles of the cams to the foot of each hump
and their object is to slowly take up the clearance between the cam levers and valve
push rods as the valves open and close thus reducing noise.
NOTE—lf the rocker spindle clamping bolt nut is unscrewed to an unnecessary extent
the rocker spindle will then move sideways, under the influence of the spring
washer, and then the thrust washer at the end of the rocker spindle may drop
out of exact location and, unless noticed and re-positioned, damage to the
flanged end of the rocker spindle may result upon re-tightening the clamping
bolt nut. Care to avoid this is necessary. (See illustration 12).
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PLAIN WASHER—MENTIONED
ABOVE.
SPRING WASHER.
PLAIN WASHER.
ROCKER.
CYLINDER HEAD.
ROCKER CLEARANCE ·008".
VALVE SPRING CAP.
CLAMPING BOLT NUT .
CLAMPING BOLT WASHER.
CLAMPING BOLT.
C U T A W A Y ON ROCKER SPINDLE.
ECCENTRIC ROCKER SPINDLE.
Illustration 12
Rocker Adjustment
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