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 testing, detailing issues with vibration, the vacuum pump, and oiling system, and listing optimal valve timings.
| Identifier | WestWitteringFiles\S\September1928-October1928\ Scan011 | |
| Date | 5th September 1928 guessed | |
| contd :- -2- Two arrangements have been tried (V.406 and 411), both being equally good. The method adopting the flats is recommended more as this does not necessitate the use of small holes. A restriction had to be fitted in the rockers V.410 to prevent the valve stems being flooded with oil. A very bad vibration of the engine in its mounting is apparent at 1325 r.p.m., the amplitude at the gearbox end is of rather alarming proportions. It would probably be advantageous to fit the support at the rear of the gearbox. When connected up to a standard autovac tank the vacuum pump does not supply sufficient fuel to maintain full throttle running - see V.407. It is thought that its performance may be improved by re-arranging the ports of the pump, as the present disposition gives a pressure at the suction port during part of the stroke. Various valve timings have been tried with the 110° camshaft now fitted, but the best power (V.412) is obtained with the following :- Inlet opens 9° after T.D.C. Inlet closes 32° after B.D.C. Exhaust opens 37° before B.D.C. Exhaust closes 1° before T.D.C. The oil relief valve does not keep the pressures very constant; it would appear that it is not large enough for the work it has to do, seeing that the pressure variation is considerable throughout the range of speed. The pressure to the rockers increases at a very great rate, (V.412). More investigation work on the oiling system is to be done in the immediate future. lms/A.C.Lovesey. | ||