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 Advance on the flywheel versus RPM for an Oil Relay system.
| Identifier | ExFiles\Box 65\1\ scan0189 | |
| Date | 12th December 1926 guessed | |
| OIL RELAY IGNITION ADV. FLYWHEEL 50 40 30 20 10 7EX. 10EX. 100% POWER 1000 2000 R.P.M. | ||