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).
Timing diagram for a 20/25 HP engine with a 5.25:1 compression ratio, showing battery and magneto ignition advance.
| Identifier | ExFiles\Box 51\5\ Scan255 | |
| Date | 12th May 1931 | |
| X5681 FLYWHEEL DEGREES 50 40 B.D.P. 30 20 10 RETARD. 0 A.D.P. 10 20 BATTERY IGNITION ADVANCE (FULLY ADVANCED AUTOMATICALLY) MAGNETO ADVANCE BATTERY IGNITION ADVANCE (FULLY RETARDED AUTOMATICALLY) IGNITION LEVER TRAVEL RETARD ADVANCE 43° 31° 13° 20/25 HP 5.25 : 1 COMPRESSION RATIO. BATTERY AND MAGNETO IGNITION TIMING DIAGRAM. X.5681. HFW 12. V. {VIENNA} '31 C.R.F. 12.5.31 | ||