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).
Graph showing ignition governor curves against engine RPM for a 25/30 model with a standard turbulent head.
| Identifier | ExFiles\Box 101\3\ scan0006 | |
| Date | 16th May 1936 | |
| SP.{Mr Spinney} 25 25/30 IGNITION GOVERNOR CURVES STANDARD TURBULENT HEAD TEST CARRIED OUT WITH SHELL NO1. AND STANDARD CHASSIS EXHAUST SILENCER. E.60660 STD: PROD: CYL: HEAD (TURBULENT TYPE.) 6:1 COMP: RATIO. STANDARD VALVES 1.4 DIA: INLET 1.225 DIA: EXHAUST STANDARD STROMBERG IND'N SYSTEM. ① IDEAL LINE (MINIMUM ADVANCE FOR MAX: POWER.) ② LINE TO CUT OUT DETONATIONS. ③ 2% POWER DROP BY RETARDING. ④ PROPOSED LINE AS GIVEN BY AUTOMATIC OF SPECIALLY PREPARED GOVERNOR. SPARK POSITION FLYWHEEL ° BTDC ENGINE R.P.M. | ||