Page:Motors and motor-driving (1902).djvu/210

178 There are still a few but extremely improbable causes for irregular firing:

Cause 10 (rare).—There may be too much play worn in the cogs of the valve gear or ignition gear. The remedy is to advance one tooth.

Cause 11 (rare).—The cog wheels of the 'two-to-one' gear may have been put together wrongly by a repairer.

N.B. Always make your own marks when taking these wheels apart, for the existing marks may not necessarily be correct. The makers often find a better position for the teeth to engage after one set of marks have already been made.

Cause 12 (rare).—It has also happened that the key or feather by which a gear wheel of the ignition or valve mechanism is keyed on to its shaft has sheered, and the wheel has moved round on its spindle, causing firing to take place at the wrong instant, and very erratic behaviour in consequence.

Cause 13.—For reasons previously explained, if water can find its way into the cylinder, misfiring may result.

Finally, remember that if your engine is misfiring or pulling badly, the fault may of its own accord very likely disappear altogether after a little running.

Evidently something wrong with the governing gear. What?

Cause 1.—The cam, which, by means of a small fitting which resembles a hammer, throws the exhaust-valve lifters out of action, is keyed to its shaft by a small screw; if this works out, as it sometimes does, the cam will move about where it likes, and leads to the fault in question.

Cause 2.—Similarly if the 'hammer' gets loose or is worn, the same result will follow.

These remarks refer to the engines of the Daimler and Panhard type.

Cause 3. In these motors the governor is usually arranged to cut out one or two cylinders before the rest; if much wear has taken place in this mechanism the trouble in question may arise.

There are also springs whose function it is to bring back the exhaust lifters into action after they have been 'cut out' by the