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).
Resistance and timing specifications for a Watford EC6d Magneto, serial number 73972.
| Identifier | ExFiles\Box 48\2\ Scan250 | |
| Date | 18th March 1925 | |
| X8796 18.3.25. EFC. {E. Fowler Clarke - Electrical Engineer} WATFORD EC6d MAGNETO No. 73972. Primary resistance (19°C) = .96 ohms. Secondary resistance (19°C) = 2,400 ohms. Timing. Condition. Advance. Retard. Make. -108° -46° Break. 40° 102° Make. 70° 132° Break. 221° 284° Range = 62° Make ratio = .833. HEW. | ||