COIL IGNITION

Hawera Star, Volume LII, 19 November 1932, Page 12

COIL IGNITION

SIMPLER THAN MAGNETO. CARE AND MAINTENANCE OUTLINED. It is interesting to note that coil ignition was the earliest electrical means of producing the spark in the combustion chamber, and its total eclipse and subsequent return to favour are without counterpart in the development of tire motor-car, states an article m an English motoring journal.. Contrary to generally accepted ideas, coil ignition is generally simpler than a magneto. Moreover, if anything does go wrong, everything is readily accessible and no particular mechanical skill is demanded in rectifying matters. The reason for its return is simple: all cars now have a large capacity accumulator on board for lighting purposes, and the almost negligible amount of current which coil ignition demands even for a six-cylinder car. Indeed, while there is a mere glimmer in the headlamps from the alcumulator there will be sufficient current from the battery to ensure a ready start (although, of course, in such an event the starting handle would have to be used), and as the quality of the spark is not dependent on the speed with which the engine is revolved, starting is definitely easier than in the case of the magneto. Unless a car has been standing by ' for months, it is most unlikely that] there would ever be insufficient current for starting purposes, and as the '• coil consists only of a number of turns j of two gauges of wire, it means that) the only thing in the circuit requiring attention or calculated to be affected by wear or neglect, is the contact breaker. This, however, can be of sturdy dimensions, with generous contact surfaces, so that it is only at widely separated intervals that even this compon-1 ent demands attention. Occasionally one should remove the distributor moulding and inspect the electrodes to which the high-tension cables are secured. This is easily j effected if the two securing springs are pushed aside. Upon inspection the electrodes should be clean and free from deposit. They should be wiped with a rag just moist with petrol, particular care being taken that. ;che qentral (contact is clean. If it should be unduly polished 'it might even be prudent to scrape it. very gently with a. blade of a penknife. I At the same time the contact spring* should be rubbed over.

KEEP CONTACTS CLEAN. We_ must be quite sure that oui make-and-break mechanism is working properly, because upon the strength of the low-tension current depends that of the high-tension surge, and consequently the spark. Contact points should meet cleanly and be free from pitting, and, broken, should be the correct distance apart, which is ,015 in. On the little spanner supplied with the car a. gauge of the correct clearance will be found, vyhich may’ be inserted between the points after the engine has been turned into such a position that they remain open. It sometimes happens that these points become dirty, and in. the case of abject neglect it is possible that they might ultimately reach a condition where no spark at all was induced. This state of affairs, however, always gives us preliminary warning with an elusive misfiring, and at the first signs of such misfiring the contact breaker should be inspected and, il necessary, cleaned. Here, again, a rag dipped in petrol will serve the purpose, except in very bad cases, when it is permissible to use a nail file, the finest grade emery cloth, or, better still, the sides of a safety match box pushed down between the points. These* points, be it noted are made from a precious metal; more than two or three strokes obviously should not be made, lest it be worn away unduly. Having finished the cleaning operations, it is, of course, necessary that the whole contact breaker should be wiped over with our friend tlv: rag-moistened-with-petrol, because the least little bit of emery can c!o a greal deal of damage. While the emery cloth is in operation, the rag, as a matter o: precaution, ought to be beneath it to catch any particles of emery that inny be detached.

It is but seldom that the gap at the points will require adjustment, and an owner may keep his car over a long period of years and find that it never varies from the gauge on the spanner. Should it do so, adjustment is a simple matter. The locking nut on the fixed contact is slackened off, while the other —to which the platinum point is affixed—is rotated half a turn, when the gauge is once more brought into play, and if the gap is found correct the lock nut can be tightened once more, great rare being taken, of course that the adjustment is not lost. In some instances it is necessary to use two spanners, to ensure that the screw does not turn when the lock nut is being tightened.

CARE REQUIRED. Care should be taken when tlie distributor is being reinstated that all the wires are inserted well into their bidders. Cases have been known where high-tension cables disturbed during cleaning operations have not been pushed right home, and have been the cause of q difficultv in starting. Incidentally, leads should always be kept separated as much as possible, and a separator is standard on the car. Further, high-tension current, with battery ignition, is so powerful that a brush discharge caused through old leads which are too close together can materially weaken the spark at the plugs; so much so, in fact, that it might be responsible for difficult starting, when renewal would lie indicated. Incidentally, where a car is housed in a garage which is known to be damp it is a good plan to smear a very little vaseline on the terminal ends of the leads. When these are pushed home there will then be no fear of a sticking lead if for any reason it has to. bn detached