CLEANING VALVE STEMS

Evening Star, Issue 21945, 4 February 1935, Page 6

CLEANING VALVE STEMS

The importance of the valves and their correct operation is not always appreciated by motor users, yet a very great deal of the efficiency and smooth running of the engine depends on the valves being in cool condition and functioning correctly. In time the valve guide gets coated inside with a sticky oil and carbon mixture which makes the valve stern move sluggishly, even when the valve is returned to its seat by a strong spring. The speed at which the valve

is dropped from the fully-open to the fully-closed position is hardly appreciated by the user, but, if it falls sluggishly, it may seat late and so seriously affect the performance of the engine. This is especially true in the case of exhaust valves, although it may, in some instances, apply to inlet valves as well. An increased efficiency of the engine may be ensured if valve stems and valve guides are thoroughly cleaned with petrol or paraffin so that all trace of carbon or oil is removed and the surfaces of the stem and guide are made quite smooth. Polishing the valve stem with emery or with a rotary movement is not advised, for that causes the formatioif of innumerable minute annular ridges which conduce to the picking up and retention of burnt oil and carbon. Valve stems and valve guides should be polished with metal polish with the movement of the polishing material in line with the stem. The polishing should he in the line of natural movement of the valve, as it rises and falls (some two thousand or more times a minute) in its guide. A little care in this matter will make for sharper closing and reduced wear of the stems and guides, with correspondingly increased power and flexibility of the engine.