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 table of performance data for various magnetos.
| Identifier | ExFiles\Box 4\5\ 05-page158 | |
| Date | 7th November 1923 | |
| -2- Magneto. | Degrees of make. | Makers make advd. | Makers break advd. | Our break advanced. | Our break retarded. | Lowest speeds for 5.5 mm. Adv. | Lowest speeds for 5.5 mm. Cent. | Lowest speeds for 5.5 mm. Retd. | Remarks. Eisemann. | 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° J.A.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 ZR6 | 156.5 -57.5 | | 99 | 99 | 133 | 56 | 105 | 150 | Advd. posn. same as makers Our retard 2° earlier than makers. Watford EC6 | 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 ELC6 | 159.5 -81.5 | | 78 | 106 | 140 | 67 | 68 | 69 | Retd. posn. same as makers. Our adv. 28° later than maker Additional text in table: CHAIN DRIVE ADOPTED. Text on right margin: A.D.M. NO 269 7.11.23 | ||