IDLING SPEED

NZ Truth, Issue 1142, 20 October 1927, Page 13

IDLING SPEED

Testing The Mixture

"Hunting" of an engine at idling speeds is a trouble very frequently experienced by car-owners. It causes increased bearings and valve wear, wastes fuel and encourages plug deterioration. ALL engines, whether they- have magneto or battery ignition, should run steadily at idling speeds, with combustion on each power stroke shown to be completed by the sound of the exhaust by the regularity of the puffs from the latter. But one so often hears engines "hunting" when they are idling, a succession of exhaust puffs being followed by a blank period, then more puffs, another blank, and so on, implying that at regular intervals the engine "cuts out." As a rule that shortcoming is ascribed, and correctly ascribed, to an over-rich mixture from the starting and slow running carburettor jet or device. In the remaining cases no form of carburettor adjustment has the slightest effect, but a cure can always be effected by increasing the width of the gaps of the sparking plugs. Several theories have been put forward to account for this, though none seems to fit the case completely.