Friday, March 26, 2010

The ignition system is one of those areas where the Beetle has a vast number of permutations regarding timing, points gap etc. A book which is primarily concerned with the subject of restoration cannot possibly cover all eventualities. Because of this, the author describes the principles of carrying out the work and advises the reader to obtain a good workshop manual to find the precise details for the car in question. Be very careful when ordering the manual; some publishers produce up to four different manuals for different years of Beetles.
Remove the sparking plugs and examine them. The nose should be a light fawn colour; if it is covered with a dry sooty layer then the engine has been running too rich, if it is covered with a sticky black layer then the

engine is burning oil, probably from the gap between a valve and its stem or past worn piston rings. If the plug ends have a glazed appearance then the engine is overheating and should not be run until the cause has been found and rectified. Check out the ignition timing and the fuel mixture for the cause of most overheating problems, and check especially for the usual causes of pre-ignition — air induction, weak mixture or timing too far advanced. Sooty or oil-fouled plugs may be cleaned and re-used; glazed plugs must be scrapped and replaced.
Clean the spark plug electrodes using a wire brush. The gap should be set using the appropriate tool at 0.23 in. (0.6 mm).
Next check the condition of the points. Remove the distributor cap and lift off the rotor arm. The points should be clean and should present flat surfaces to each other; if they are dirty then they may be gently cleaned; if they are pitted or if one has a hollow and the other a matching protrusion, they should be changed. In either case, the gap will have to be re-set.
Remove the spark plugs and take the car out of gear so that the engine may be turned over by hand. Turn the engine until the points cam is directly on top of a lobe and the points gap is consequently at its greatest. Place a 0.016 in. (0.4 mm) feeler gauge in the gap; it should enter easily with the tiniest amount of drag. If adjustment proves necessary, slacken the securing screw and adjust the points using a screwdriver in the notch provided. Tighten the securing screw then re­check.
It is advisable to check the ignition timing, and it is essential that the timing is checked after the points gap has been re-set. There are two methods of doing this; static and dynamic. The advantage of static timing is that no special tools save a 12V bulb test lamp are needed; the advantages of dynamic timing is that it also checks (where applicable) both the mechanical and the vacuum advance mechanisms, and it is inherently more accurate. To carry out a dynamic timing check you will require a stroboscope. These are low-cost items, but always try to obtain one which will give a reasonably bright light; some are so dim that you cannot see the timing marks by their light in normal daylight. You will also need some typists' correction fluid.

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