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 of ignition advance curves for the 20/25 HP chassis at different engine loads.
| Identifier | ExFiles\Box 163\7\ img185 | |
| Date | 24th February 1932 guessed | |
| QUARTER LOAD HALF LOAD FULL LOAD R.R. 20/25 H.P. CHASSIS IGNITION ADVANCE CURVES. ENGINE DEGREES ADVANCE R.P.M. | ||