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 magneto sparking speeds at different advance positions.
| Identifier | ExFiles\Box 48\2\ Scan229 | |
| Date | 4th February 1925 guessed | |
| -3- Contd. gear wheel with the pinion is correct; incorrect meshing being indicated by an uneven rattle emanating from the distributor end of the magneto. (7) The slowest speeds at which regular sparking will occur on 5.5 mm. gaps in air shall now be ascertained and shall not exceed:- for (a) Fully advanced position 280 r.p.m. " (b) Central position 210 r.p.m. and " (c) Fully retarded position.190 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. EFC. {E. Fowler Clarke - Electrical Engineer} | ||