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).
Excess oil issue on the Bentley Large Bore engine and the recommended modifications to the valve rocker lubrication system.
| Identifier | ExFiles\Box 82\4\ scan0241 | |
| Date | 5th February 1936 | |
| To / Jmr. Hs{Lord Ernest Hives - Chair} BY from Mx{John H Maddocks - Chief Proving Officer} GRY{Shadwell Grylls} x200 Mx{John H Maddocks - Chief Proving Officer}/CH8/T5.2.36. BENTLEY LARGE BORE ENGINE. When we received the first of this type of engine on test it was found that there was an excess of oil from the rockers to the valve side of the engine, to the extent that at medium speeds the valve springs were covered with a cascade of oil. In the light of past experience we knew that this will lead to high oil consumption, etc. The valve rocker on the big bore engine is of new design and has a restricted oil passage to the push rod side, as compared with the previous type. We tried increasing the small feed hole in the new rocker as much as could be done with safety. This resulted in a slight improvement, but it could not be considered satisfactory. Further investigation showed that the oil holes in the push rod side of the rocker did not coincide with the feed hole in the shaft, It was necessary to drill a new set of feed holes approximately 64° from the existing holes in an anti-clockwise direction looking from the front of the engine, the original holes being plugged up. With this modification we consider that the lubrication is satisfactory and there is no excess of oil to the valve side of the engine. We recommend that all rocker shafts should have the feed holes in the shaft moved to coincide with the hole in the rocker. (2) that the small delivery hole on the push rod side of the rocker be increased to .094". With regard to No.2. this may not be possible on account of mechanical strength. | ||