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 plotting firing position against RPM for a single cylinder engine with a 5.2 to 1 compression ratio.
| Identifier | ExFiles\Box 65\4\ scan0320 | |
| Date | 10th November 1925 guessed | |
| IGNITIONS USED SINGLY. SINGLE CYL 5.2 TO 1. RATIO. FIRING POSITION. DEGREES OF CRANKSHAFT. TOP CENTRE. 0° -10° 10° 20° 30° 40° R.P.M. 250 500 750 1000 1250 MAX TORQUE. B A NO DETONATION WITH NO DETONATN THERE IS LOSS OF POWER 4 | ||