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).
Comparative data table for various magneto models and their performance characteristics.
| Identifier | ExFiles\Box 48\3\ Scan097 | |
| Date | 6th June 1919 | |
| -2- A.{Mr Adams} Magneto. | Degrees of make. | Maker's make advanced. | Maker's break advanced. | Our break advanced. | Our break Retarded. | Lowest speeds for 5.5 mms. | Remarks. | | | | | | Adv. | Cent. | Retd. | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Watford. | 154.5 | -57° | 97.5° | 97.5 | 131.5 | 150 | 250 | 340 | Magneto No.45638. " | 155 | -59° | 96° | 94.5 | 128.5 | 156 | 226 | 320 | " " 45462. " | 163.5 | -78.5° | 85° | 85° | 117° | 160 / 186 | 140 | 136. | Maker's range. " | 160.0 | -92° | 67° | 96 | 130 | 160 | 150 | 150. | Retd posn. same as o maker's. Adv.posn. 29° later then maker's. R.{Sir Henry Royce} Bosch. | 82.5 | +11.5° | 94° | 94 | 128 | 260 | 170 | 246. | Adv.posn. same as makers Retd.posn. 2.5° earlier than maker's. U.S.A. Bosch. | 153 | -53.5° | 99.5° | 99.5 | 133.5 | 120 | 162 | 240. | Adv.posn. same as makers. Retd.posn. 3.5° earlier than maker's. U.S.A. Bosch. | 155.5 | -79° | 76.5° | -- | -- | 150 | 250 | 330 | Maker's range. Dixie. | 73.5 | -20° | 53.5° | -- | -- | 180 | 180 | 185 | Low speed sparking unaltered by advancing. Conner. | 78 | +14.5° | 92.5° | 107 | 141 | 350 | 260 | 170 | Retd.posn.same as makers Adv.posn.14.5° later than maker's. B.T.H. | 100.0 | -27.5° | 72.5° | 62.5 | 96.5 | 244 | 192 | 220 | Datum slightly indefinite. Final adv. not secured owing to fouling. Cont | ||