SECTION K16
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ADJUSTING CAM TIMING CHAIN
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It is found that slackness of the cam chain can
result in snatch, jarring shocks being delivered to
the contact breaker and auto advance mechanism.
This causes premature wear on these parts. We
specify that the chain tension should be checked at
5000 mile intervals but, naturally, any obvious
slackness evidenced by noise in this area should be
taken up, irrespective of mileage. Adjust the cam
change tension to between 1/8 in. and 3/16 in.
slack (that is, up to down movement) on the top run
of the chain. To do this necessitates removal of
the contact breaker and auto advance mechanism (use
the withdrawal bolt 06-0934 for the auto advance
cam). Next take off the timing cover, and the cam
chain and slipper tensioner are exposed. The oilway
exposed by removal of the cover must be blocked to
prevent the loss of oil. Note that chain tension
can only be adjusted correctly if there is no play
in the intermediate spindle.
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To check the chain tension, remove the sparking
plugs so that the engine will turn easily and use a
9/16 in. Whit. socket or ring spanner on the
camshaft sprocket nut and turn slowly
anti-clockwise so that the lower run of the chain
will be kept tight on the slipper and a true check
of the tension can be made on the top run.
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In this way the spanner will control the
alternating load of the valve springs on the
camshaft and it will be easy to find any tight spot
to which the tension should be adjusted as
described.
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To increase chain tension, slacken the two nuts
securing the slipper and lift it a little at a
time, checking at each stage atter nipping up the
nuts whether the tension is correct. When the
correct tension is achieved secure the slipper nuts
to 180 lb. in (15 lb. ft.).
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It is most important when refitting the timing
cover to use the camshaft oil seal guide 06-1359 to
avoid damage to the seal in the timing cover.
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