From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Engine noise investigation, covering piston knock, rocker mechanism, timing gears, and valve mechanism issues.
| Identifier | ExFiles\Box 19\7\ Scan120 | |
| Date | 25th September 1928 guessed | |
| CONTD :- -2- small elbow fitted on to the induction pipe. This change has been made in order that the mechanical noise of the engine could be studied more carefully: The Claudel carburetter making so much suction noise as to render this very difficult. On starting up from cold all the pistons knock very badly; but the noise disappears after about 5 mins. (or less) light running. (The pistons are the single-bolt pedestal type E.7751 S with lower scraper rings to Lec.2554). When the engine has been started from cold and run for a few mins. the rocker mechanism becomes very noisy, especially above 1500 r.p.m. The noise may be reduced by cooling the engine water. After some hard running, the noise is much less, but still very objectionable. At low speeds the valve mechanism is very quiet. The rocker cover magnifies the noise when it is screwed down tightly; this is probably due to the two holding-down nuts allowing too much drumming of the cover. The effect of employing more holding-down nuts will be investigated at the earliest opportunity. The timing gears have developed a whine, and they also rattle at low speeds. This is now being corrected. The eccentric drive of the vacuum pump, (stated to have shewn signs of seizing in a previous report) has been re-examined after a further 9 hrs. running and found to be quite O.K. Investigation work on the noise of the valve mechanism, also work to ascertain the minimum necessary tappet clearance is to be carried out as soon as the engine is again in a running condition. Hs{Lord Ernest Hives - Chair}/A.C.Lovesey. | ||