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).
Technical data sheet detailing resistance values, point gaps, and contact breaker timings.
| Identifier | ExFiles\Box 49\5\ Scan223 | |
| Date | 10th December 1920 | |
| R.R. B&S (100 T) S.H. 738. 10-12-20. G. {Mr Griffiths - Chief Accountant / Mr Gnapp} 2947 -6- Contd. (18) Primary resistance :- '40 ω at 18°C. Inst 42. 1.5 volt range. 1.5 amp range. (19) Secondary resistance :- 3,200 ω at 12°C. Inst 42. 15 volt range. Inst 22596. ma. range. (20) Secondary milli-amperes :- Horizontal position :- 11.9 Vertical position :- 8.1 (21) Platinum point gap :- .026" MADE AT CROXLEY (22a) Platinum point gap :- .020" Contact breaker timing :- Make. Break. A. {Mr Adams} -54 +103° B. -19.5 138 Retarded. Advanced. Make. 161° 127° Break. 318° 283° Make. 340° 305° Break. 138° +103° Make ratio :- .873. | ||