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 performance tests for valve bounce, oil consumption, and oil pressure.
| Identifier | ExFiles\Box 6\6\ 06-page230 | |
| Date | 1st June 1937 | |
| -4- Valve Bounce (Continued). As designed, without bottom tappet springs :- (1) RS.{Sir Henry Royce's Secretary}500 springs bounce at 3600 R.P.M. - 35 lbs. seat. RS.{Sir Henry Royce's Secretary}560 " " " 3800 R.P.M. - 42 " " RS.{Sir Henry Royce's Secretary}540 " " " 4050 R.P.M. - 58 " " The length of the springs in the closed position is 1.570. (2) Similar springs on standard Bentley or 20 H.P. valve gear do not have bad surge periods as Wraith. These periods range between 3000 and 4000 R.P.M. (3) It is impossible to use the RS.{Sir Henry Royce's Secretary}540 springs without increasing the valve closed length, on account of the nearness to choc-a-bloc in the open position. (4) We intend running 15,000 miles with valve washers (RS.{Sir Henry Royce's Secretary}541) to overcome choc, which will decrease the seat loading from 58 lbs. to 50 lbs. and assumed commencement of valve bounce at 3900 R.P.M. This, up to the present, is the best available combination. Oil Consumption. Over the one-hour run at 4,000 R.P.M., the oil consumption came out at 3.00 pints/hr. This is rather higher than the average of initial runs, which comes out at 2 pints/hr. It is not advisable to alter anything until we see what the road figure comes out at. In the meantime Rm{William Robotham - Chief Engineer}/Mths.{Reg Matthews} is going to carry out a test regarding the trueness of the bores when bolted down in position. Oil Pressure. Other than having to adjust the relief valve springs to give the correct pressure, the layout appears good in respect of not creating excessive pressures at high speeds or when continued. | ||