MYSTERY AILMENT LOCATED

Southland Times, Issue 23649, 26 October 1938, Page 3

MYSTERY AILMENT LOCATED

IMPORTANCE OF TAPPET CLEARANCE Unexpected factors sometimes have a major effect on the performance of a motor-vehicle. An Auckland owner of a small. English car, with a 10 horsepower side-valve motor, was disturbed to find that his machine was steadily losing in performance. While continuing to start readily, and to run smoothly enough, it steadfastly refused to pull, until hills normally taken in top required a change-down, and those for which third was the usual ratio brought the car down to low. All likely components were checked. The spark plugs, which had given some 15,000 miles’ service, were replaced with the best obtained. The carburetter was cleaned, the filters checked, and the distributor examined. The breaker-points were found to be pitted and a slight improvement resulted from cleaning and resetting them, but performance was still well below standard. Brakes were checked for possible binding, lubrication of wheels was done as a precaution, and in fact practically the whole car was gone over. In a moment of inspiration, and alter a careful read through his manual, the owner thought of the tappets, those hard-working little chaps coyly hidden behind their oily cover. Two spanners, a feeler-gauge and a certain measure of contorted effort showed that on six of the eight tappets, there was no clearance at all. The other two were correct. An hour or so was occupied in setting the clearances with the great accuracy possible, and a test run quickly restored the owner’s faith in his car.

Performance had improved by fully 50 per cent., and the owner no longer had the humilation of being passed by everything but trolleys on the slightest grade. In fact, he claims that the car is going as well as when it was new, in spite of the better part of four years’ use.