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).
Comparison table of various magneto specifications and performance data.
| Identifier | ExFiles\Box 4\5\ 05-page304 | |
| Date | 21th August 1924 guessed | |
| 29. Magneto. | Degrees of make. | Makers make adv. | Makers break advd. | Our break advanced. | Our break retarded. | Lowest speeds for 5.5 m/m.{Mr Moon / Mr Moore} Adv. | Lowest speeds for 5.5 m/m.{Mr Moon / Mr Moore} Cent. | Lowest speeds for 5.5 m/m.{Mr Moon / Mr Moore} Retd. | Remarks. Risemann. | 150.5 | -53.5° | 97° | 97° | 131° | 155 | 177 | 238. | Advanced position as makers but more advanced than to allow proper high speed sparking by 7° U.S.A. Bosch DUZ6. | 156.5 | -58 | 98.5 | 98.5 | 132.5 | 102 | 124 | 180 | Advanced posn. the same as makers. Retard posn. 1° earlier than makers. U.S.A. Bosch ZR.6. | 156.5 | -87.5 | 99 | 199 | 133 | CHAIN DRIVE ADOPTED. 156 | 105 | 150 | Advd. posn same as makers. Our retard 2° earlier than makers. Watford E06. | 158.5 | -74.5 | 84 | 84 | 118 | Irregular sparking at all speeds. | | 245. | Advd. and Retd. position same as makers. Range limited by movable sleeves. Watford ELO6. | 159.5 | -81.5 | 78 | 106 | 140 | 67 | 68 | 69 | Retd. posn. same as makers. Our adv. 28° later than makers. Scintilla AC6-A.{Mr Adams} | - | - | - | - | - | 250 | 260 | 280. | L.S. Tests by HEW. Scintilla AM6-A.{Mr Adams} | 83 | 13 | 96 | 96 | 13 | 220 | 330 | 410 | Tests by CAP. Scintilla AM6-A.{Mr Adams} | 78 | 16 | 94 | 94 | 16 | 150 | 200 | 290 | Tests by HEW. Scintilla AM6-A.{Mr Adams} | - | - | - | - | - | 140 245 | 190 300 | 230 385 | * * Scintilla AG6-A.{Mr Adams} | 81 | 16.5 | 97.5 | 97.5 | 16.5 | 160 | 220 | 290 | * * | ||