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 of ignition firing position against engine RPM for a single-cylinder engine with a 5.2 to 1 compression ratio.
| Identifier | WestWitteringFiles\N\July1925-September1925\ Scan296 | |
| Date | 19th August 1925 guessed | |
| 4 IGNITIONS USED SINGLY. SINGLE CYL 5.2 TO 1. RATIO. FIRING POSITION. DEGREES OF CRANKSHAFT. 40° 30° 20° 10° TOP. CENTRE. 0° -10° R.P.M. 250 500 750 1000 1250 MAX TORQUE B A NO DETONATION WITH NO DETONATION THERE IS LOSS OF POWER | ||