CYLINDERS THAT MISS

Hawera Star, Volume L, 17 May 1930, Page 13

CYLINDERS THAT MISS

There are three ways of locating misfiling cylinders: (1) If the engine is warm, touch the various spark plug shells with the: fingers. If one cylinder has been missing consistently its •spark plug shell will be considerably cooler than the others. If a moistened finger tip he touched to a spark plug shell in a cylinder tin,it is firing, sizzling may be.- noted, while the spark plug -on the missing cylinder will not produce sizzling. This test may be made with the engine running or just shut off. Remember that a disagreeable shock will be experienced if you touch a spark plug terminal while the engine is running.

(2) If tlie engine is provided with compression taps these may be opened singly while the engine is running above idling speed. IT no flame is observed the cylinder is missing. " If the tap is so constructed or so located that the flame cannot be seen, the volume of sound issuing from it may be taken as a guide, the missing cylinder being much weaker than the others. Similarly, the force of the explosion may he felt hv placing the thumb about half an inch away from the open tap. Compression taps sometimes become clogged with carbon, in which case the tests described may prove impossible unless they are cleaned.

(3) Short-circuit the spark plug terminals one by one with a screw-driver provided with a wooden handle. An unpleasant shock will be received if there is any metal in the handle. With the engine running* allow the shank of the screwdriver to touch the spark plug terminal, while the tip of the Screwdriver is held against the casting. When lx plug is thus short-circuited, missing is produced in this cylinder. Therefore, it is plain that when the plug in the missing cylinder is shortcircuited, no difference will be heard ■in the exhaust note and no drop in the engine speed will be noted, whereas, whenever the spark plug in a good cylinder is short-circuited, another miss will be noted and the engine speed will drop, due to the cutting; out of this cylinder.

When the car “jibs” make sure that the ignition is switched on and that there is petrol in the carburettor. Tim petrol tap should preferably be, turned off when the engine is not running; do not forget to turn it on again, before re-start mg. If, with a full tank and the petrol turned on no petrol reaches the float chamber, there may be a stoppage in the petrol pipe. This should be disconnected and cleaned out. Possibly, however, the auxiliary petrol filter between the tank and the float chamber may have become clogged. These troubles are caused }>v pouring petrol into the tank without using a filter.