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).
Requesting experimental modifications for a 20,000 turn ignition coil and a new type of ballast resistance.
| Identifier | ExFiles\Box 69\1\ scan0144 | |
| Date | 19th September 1928 | |
| To EY, from EFC. c. EY/RD. RHC.{R. H. Coverley - Production Engineer} X.8710 EFC2/T19.9.28. 20,000 TURN IGNITION COIL. Would you please instruct experimentally an otherwise standard ignition coil but of 20,000 turns (secondary in place of 18,000, in which case the air space between the secondary and case is slightly reduced accordingly. We have reason to believe that this will overcome the occasional firing failures of present std. coils in exceptional circumstances on experimental cars. X8720. Will you also please instruct for similar purposes a ballast resistance half way between single and double types we have used. The same gauge of wire should be put on as is used on the double ballast resistances, and 3/4 of the length. EFC. | ||