NO CYLINDER HEAD WASHER IS USED ON THE A.J.S. CAMSHAFT
ENGINE.
Originally the faces of the cylinder head and barrel are ground in. and providing
they remain clean and unscratched can be replaced without any jointing compound or
attention other than washing with petrol. If however, either of the faces are marked, causing
compression leaks, remove the two holding down studs by two nuts together on the thread
of the stud to unscrew this, then smear the faces with very fine emery paste, and grind in
the same manner as in valve grinding until all the marks are removed. Be sure to remove
all traces of emery paste with petrol after this operation.
Actually it is much better and easier to grind in these faces when both the cylinder
barrel and head are away from the engine; there is then no danger of emery paste finding
its way into the engine and the cylinder head can be rotated freely on the barrel. When the
Cylinder head is again in position, replace the nuts to the studs which protrude through the
cylinder barrel, follow on with the long cylinder head bolts, and lastly, the short cylinder
head bolts. Tighten these down together, not independently. Before replacing the rocker
box make sure that the small hardened caps are fitted over the valve ends, and place the one
rocker box bolt nearest to the exhaust lifter into its hole, then locate the threaded end of the
camshaft into the centre of the chain wheel, afterwards pushing out the tool holding this in
position. Watch that the rubber washer between the rocker box and the chain cover settles
into position properly.
When the chain wheel is in position on the shaft and the rocker box tightened down
it is possible to feel the chain tension. Any excessive slackness after the machine has com-
pleted a considerable mileage can be taken up by fitting washers of the correct thickness
under each leg of the rocker box. It is essential however, that approximately 3/8in. or ½in.
of side movement always exists in the chain.
A small plug is situated about half way up the camshaft drive cover: when this is
removed it is possible to insert a narrow screw-driver to ascertain that the tensioner blade
is following the chain and not idle against the side of the cover.
Providing the flywheels have not been rotated the pegged plate can be replaced
through the chain wheel and sleeve, but if the flywheels are not in the original position, turn
the engine slowly over until T.D.C. of the compression stroke is reached: the hole in the
sprocket and that in the sleeve should then coincide although sometimes the shaft has to
be rotated slightly to bring the two into line so as to replace the pegged plate. A rough
check for the valve timing is, that with the piston on T.D.C. and the contact breaker points
just breaking with the ignition lever fully retarded, both the hole in the chain wheel and the
sleeve should be together at 50° to the right from T.D.C.
HOW TO USE THE A.J.S. VALVE GRINDING TOOL.
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