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).
Investigation into engine noise, focusing on tappets and the chain and tensioner.
| Identifier | ExFiles\Box 113\5\ scan0171 | |
| Date | 27th October 1936 | |
| -2- registered by an electric bulb. The variation in reading measured was never more than .001. (5) Noise. The tappets were set at .002 clearance with engine cold, to give a consistent clearance of .006 with the engine hot. With the rocker cover fitted, but not tightened down, the only noise to be heard was the valves on their seats. This was not serious, the degree of noise being better than the standard 4.1/4 Litre Bentley, and about the same as the standard 25/30. With the rocker cover tightened down, the noise was amplified to about the degree of the 4.1/4 Litre Bentley. It is our opinion that the tappet cups fitted between the rocker and valve stem almost eliminate tappet noises. This is a first impression however, and a direct comparison is worth while, leaving out the cups, if this could be arranged. (6) Chain and Tensioner. When the engine is started from cold, the oil film can be heard breaking between chain and sprocket, but only when standing at the front of the engine, and this noise dies away almost immediately. The chain otherwise cannot be heard in operation, until a period comes up on the tensioner. This period starts at 1950 RPM. and goes out at 2450 RPM. The period is the same at full throttle as part throttle, and is there decelerating as well as accelerating. This feature has been watched through a window in the front of the engine, and it is seen that the chain and tensioner flap about in this period. It is proposed to carry out a series of tests to find the source of this period. RM{William Robotham - Chief Engineer}/C.T.Salt. Attached: Curves S.8 & S.9. | ||