LOSS OF EFFICIENCY

Rotorua Morning Post, Volume 2, Issue 332, 20 September 1932, Page 2

LOSS OF EFFICIENCY

IMPORTANT FACTORS IN REGAINING LOST PERFORMANCE. METHODS OF DETECTION. It often happens that cars lose a noticeable amount of efficiency without apparont reason. Compression is normal, cylinders do not contain an excessive amount of carbon, and the earburetter is clean and correctly adjusted. A common cause is neglect to clean carbon deposit thoroughly from the ports beneath the valves when the engine is being decarbonised. On raeing engines the insides of the ports and induction and exhaust manifolds not only are kept clean, they are accually polished to mirror brightness, and it is found that the freer gas ilow thus obtained materially improves power. Another vsry important factor is the condition of the valve springs. These may be considered to have lost sufficient power after 10,000 miles of service to warrant replacement, which is not expensive even if the car is an unusual model and they must be specially made. New springs should he one of the first experiments made with a second-hand sports car the performance of which is thought to be under par. Another 'early experiment should be the fitting of a complete new set of plugs, correctly selected from the plugmaker's chart for the make and model of car. Plugs often deteriorate to a degree when they cease to give perfect ignition without any audible misfiring. At high speeds even a complete misfire may be difficult to detect. Should the new plugs not make any improvement they will be needed ultimately. Needless to say, the rest of the ignition system should

be above suspicnon. This apphes rarticularly to the high-tension wires, which can be depended upon to leak current when old and perished. Highspeed misfires will be caused by in_ correct contact-breaker setting and too weak a return spring or a stiff pivot at this point. The distributor must be clean and its carbon brush in good condition. The whole superiority in perj'ormance of sports over a normal tyoe car depends upon its ability to develop power at iiigher engine speeds. For this reason points such as those mentioned are specially important with cars of this class. It must not be forgotten that all the reasons for poor performance are not to be sought in the engine; any waste of power between the crankshaft and the road will contribute. One of the most likely is neglected lubrication of gearbox, back axle, a?id universal joints. Too much of tbe thick oil used in transmissions also will cause power absorption, and for transmissions that will retain it engine oil is excellent and more efficient.

Most owners forget that brake gear needs lubrication, and the result is not only that the brakes become a great deal less effective because of the amount of effort which '-.as to be expended in overcoming friction in Ihe linkage, hut also that they are pre. vented from releasing fully. Then power, fuel, and friction linings ari wasted. It is a very good plan to dismantle the brakes themselves at least onee a year so that all moving parts mside the drums can he cleaned and lubricated. In few cars it is possible to lubricate such points as the brakeshce pivots from outside. On most British cars the drums can be removed without disturbing the fixed hubs if some countersunk screws hetween the wheel studs are taken out.