A.J.S. 16 Instruction Book - Engine Service
ENGINE SERVICE
TAPPET ADJUSTMENT—SINGLES
The top ends of the two long push rods have screwed extensions. These are locked in
position by nuts, thereby providing tappet adjustment.
The correct tappet clearances, on all models, with valves closed and engine warm (not
hot) is
N I L .
This means the push rods should be free enough to revolve and, at the
same time, there should be no appreciable up and down play.
Prepare to adjust tappets by:
Set piston to T.D.C. (both valves closed).
Remove the three nuts, and fibre washers under them, retaining tappet cover to rocker
box.
Take away cover.
Adjust tappets on all 350 and 500 models by:
With spanners, hold the sleeve 5, either valve (illustration 11) and slacken lock nut 2.
Then screw, in or out, the head 3 until the clearance is nil.
Tighten lock nut 2 and re-check the clearance.
Finally
Check adjustments so that, with no up and down movement, the long push rods are free
to revolve when the valves are closed.
Illustration 11
Tappet adjustment
Complete adjustment by:
Replace rocker tappet cover taking care to replace the fibre washer that is under each
retaining nut.
As mentioned elsewhere do not over-tighten the nuts because the joint is made with a
rubbe fillet and undue pressure is not necessary.
NOTE—In normal conditions tappet adjustment should not be necessary more frequently
than about every five thousand miles or after decarbonising and grinding valves.
If adjustment is found necessary more frequently the cause should be investigated
at once.
1
2
3
INLET ROCKER ARM (TAPPET END).
N U T ,
LOCKING
ADJUSTING
CUPPED
SCREW.
CUPPED ADJUSTING SCREW.
4
5
6
CUPPED ADJUSTING SCREW A N D LOCK
N U T .
SLEEVE TO A C C O M M O D A T E ADJUSTING
S C R E W , O N TOP END O F PUSH ROD.
EXHAUST ROCKER ARM (TAPPET END).
26