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).
Table of specifications for an automatic ignition advance mechanism.
| Identifier | ExFiles\Box 48\2\ Scan069 | |
| Date | 13th July 1923 guessed | |
| 7A Automatic Advance. Total range:- 33° Advance commences:- 270 r.p.m. " finishes:- 3,300 " " Speed for advance of:- 5° = 800 " " 10° = 1160 " " 15° = 1600 " " 20° = 1900 " " 25° = 2250 " " 30° = 2750 " " 33° = 3300 " " | ||