The contact breaker becomes accessible following removal of the screws “G” which
retain cover “F” (Fig. 6). Turn the engine until the points are fully opened and insert
a feeler gauge between them. The correct gap in this position should be ·012 in. (·3
mm.) and if it is found to be incorrect, slacken screw “E” (Fig. 2) and turn the
eccentric pin “H” until the correct gap has been restored, finally tightening screw
“E”.
Fig.
2.
The Contact Breaker
Contact Breaker Cam Lubrication.
Apply a very small amount of thin grease (preferably of the high melting point
type) to the felt pad which lubricates the cam. Do not use an excessive quantity
because it is most important that the contact points are kept free from lubricant,
otherwise mis-firing and difficult starting may occur.
Cleaning
If the contact points are burnt or blackened, clean with a fine carborundum stone or
very fine emery cloth, afterwards wiping away any trace of dirt or metal dust with a
clean petrol-moistened cloth.
Ignition Timing
The ignition timing is accurately set within very close limits and there is neither
provision, nor necessity, for manual adjustment of the setting. It cannot be too
strongly emphasised that the ignition timing is correctly set for satisfactory engine
performance and that any attempt to “improve” on the manufacturer’s setting should
be avoided, since it has been determined after careful development.
The contact breaker cam “A”, Fig. 2, is mounted on a tapered extension of the
engine main shaft and its position with reference to the piston is therefore constant.
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