USELESS WORK

NZ Truth, Issue 1152, 29 December 1927, Page 13

USELESS WORK

Enthusiastic Novices Do Too Much

Among the huge brotherhood of motor drivers is a section whose chief pride seems to lie, not in driving, bu% in cleaning their cars, and their engines are models of

scrupulous care.

COME of them even go so far as to remove the plugs after every run or couple of runs, and carefully wipe the points free of oil and any little carbon that may be on them.

They do not realise that the spark plugs are far better left alone. The points of a plug are not the parts that need cleaning, as the spark itself burns any deposit away. The insulator is the danger, point, and if it becomes covered with a heavy black coating of carbon, from operating with too rich a mixture or from the use of too much oil, it will be helpful to clean it.

The danger from a coating of that sort is that it permits the current to leak away through the soot instead of jumping at the gap, and when that occurs missfiring results.

A heavy, dry, powdery black coating is usually due to too rich a carburettor setting, while a more crusty coating, which may in some cases be slightly oily, shows excessive lubrication, or piston rings in bad condition.

A polished ibrown surface is normal, and means that no attention is necessary. When, cleaninsr is done, care should be exercised that the polished surface of the insulator is not scratched, as that causes carbon to deposit more rea'dily and reduces the insulating ability.

Petrol and a cloth may be used for cleaning, or in some cases, a mildly abrasive cleaner, such as is used for cleaning pots and pans.

While attention to points has toeen indicated as more or less superfluous, there is one case where points cause trouble. It is when they burn thin and cause missfiring 1 by getting red hot from the combustion of the previous fuel chai-ge.

When that occurs it is probably time for a new set. Makers recommend a new set about once a year, because of the weakening of the insulator as well as point tdeterioration.