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 the make ratio-speed curve for a new standard contact breaker.
| Identifier | ExFiles\Box 61b\2\ scan0093 | |
| Date | 27th July 1928 | |
| R.R. STANDARD BATTERY IGNITION. MAKE RATIO - SPEED CURVE OF NEW STANDARD CONTACT BREAKER TO LEC 2460. MAKE RATIO .2 .3 .4 .5 .6 .7 DISTRIBUTOR SPEED. rpm. 200 400 600 800 1000 1200 1400 1600 1800 H.E.W 27-7-28 | ||