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).
The desired ignition governor advance curve for the Wraith III model.
| Identifier | ExFiles\Box 108\2\ scan0042 | |
| Date | 4th March 1938 | |
| To Rm{William Robotham - Chief Engineer}/RC.{R. Childs} from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} c. BY/RD. WRAITH III IGNITION GOVERNOR. Now that the hand control Advance and retard has been deleted from the governor it is desirable not to have the static setting any earlier than TDC by reason of firing back when started by hand. Slow running is also benefited by running at TDC rather than before TDC. Irrespective of whether we use a Delco or R.R. distributor, the following curve is desired and every effort should be made to obtain this governor characteristic. Static setting at TDC. Flywheel degrees. Engine Advance before TDC. RPM. Start 250 5° to 6° 500 16° to 17° 1000 23° to 24° 1500 28° to 29° 2000 32° to 33° 2500 34° to 35° 3000 Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||