IGNITION TROUBLES
The ignition system is the greatest producer of trouble, and the reason is usually difficult to locate. Any interference with the flow of the current, or leaks by which it evades passing over the entire circuit, will cause irregular running or the stopping of the engine, and the circuit must be maintained in the best possible condition in order to prevent these as much as possible. The wires should be well insulated, the insulation of the secondary circuit being heavier than that of the primary because of the higher pressure of the current that must be retained. The constant vibration to which the wires are subjected requires the use of cable composed of a number of strands of fine wire rather than a single heavy wire, for the latter is much more liable to be broken; but in securing the end of a cable under a nut, great care must be exercised that all of the strands are bound. A single strand is hardly noticeable, but if it comes into contact with uninsulated metal, it will permit the current to leak. In making connections, the best plan is to solder the end of the cable to a copper or brass terminal which holds the strands secure, and gives a firm bearing for the nut. Before making connections the terminals should be scraped bright, and after running the nuts down firmly, covered with vaseline to prevent corrosion. Corrosion of copper or brass produces a greenish deposit (copper sulphate) which is an insulator, and when it forms between the terminals of the conductor it produces high resistance, cutting down or even preventing the flow of current. A worse effect of corrosion is to bind the nuts on the screws, preventing their removal. A loose connection presents resistance to the flow of current, and the current will flow irregularly, as the vibrations bring the terminals together or separate them. A wire broken at a terminal is easily seen, but when a break occurs inside of the insulation, it is more difficult to detect. When a broken wire is suspected, its circuit may be located by testing, and new wires laid, one length at a time, until the faulty one is replaced. It is poor economy to use cheap wire, for the best is none too good for the hard use to which it is put. The wearing away of insulation by chafing will produce a short circuit, and the wires should be prevented from coming into contact with any part of the car or engine in such a manner as to give this result.