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).
Test report on the high and low-speed sparking characteristics of various magnetos.
| Identifier | ExFiles\Box 48\2\ Scan092 | |
| Date | 9th May 1924 | |
| Contd. -9- EFC {E. Fowler Clarke - Electrical Engineer} 1/T9.5.24. (a) (b) (c) (d) Safety gap. Scintilla No.26485. 8.4 2.7 1.0 .7 11.5 mm. Scintilla No.34937. 10.95 6.75 2.4 1.15 11.8 Watford EO6. 6.5 5.3 3.5 2.4 8.5 (N.B. The figures for the EO6 will probably be somewhat better than this on an up-to-date machine. The safety gap is that for an up-to-date machine). (15) Sparking Characteristics. - High speed. The maximum regular spark gaps for high speeds were as follows :- Hand range only. Fully advanced. Central. Fully retarded. 1st. Scintilla. 6.5 8.5 9.5 2nd. " 9.1 10.1 10.8 Hand range 20°. (16) Low speed sparking characteristics. The lowest speeds at which regular sparking occurred on 5.5 mm. gaps for (a) Fully advanced position } (b) Central position } Hand advance only. (c) Fully retarded position } were found to be :- SPEED. Magneto. Advanced. Central. Retarded. 1st. Scintilla 220 350 410 2nd. " 150 200 280 Watford EO6. 210 200 200 the EO6 figures for production test being:- 270 210 200. | ||