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).
Table of engine RPM versus crank degrees advance.
| Identifier | ExFiles\Box 101\3\ scan0074 | |
| Date | 7th June 1937 | |
| -2- Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}13/R.7.6.37. Engine Crank Degrees. R.P.M. Advance. ( 400 ............... Start ( 500 ............... 2° (750 ............... 9° limit of(1000 ....... 15° ± 50 RPM(1250 ....... 20° (1500 ............... 25° (1750 ............... 30° Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||