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).
Specifications for minimum sparking speeds of a magneto at various ignition timing positions.
| Identifier | ExFiles\Box 57\2\ Scan155 | |
| Date | 20th December 1926 guessed | |
| -3- Contd. for (a) Fully advanced position 250 r.p.m. (b) Central position 190 r.p.m. (c) Fully retarded position.150 r.p.m. Note. The minimum sparking speed for each of the three positions can be taken to be that speed at which 72 consecutive sparks, without missing, are given by the magneto at some time within a period not greater than 5 minutes. RFC. | ||