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).
Modifications to the battery ignition system for cars equipped with a self-starter.
| Identifier | ExFiles\Box 34\1\ Scan007 | |
| Date | 10th July 1917 | |
| To Wor.{Arthur Wormald - General Works Manager} for Mr. Ellis } from R.{Sir Henry Royce} EH. } X. 2512. c. to EY. R2/B10.7.17. X.2814 X.3199 X562 X.3716 X1819 X2512 X.543 X699 X.186 RE BATTERY IGNITION FOR CARS &C. Where a self starter is used, as in the case of 7 CA, we might quite well abandon the use of the trembler. It will be necessary if we do so to fit non-inductive resistance made of thin iron wire, or other metal of a high temperature co-efficient, so as to control the current and prevent it becoming much greater than the necessary amount to give the required length of secondary spark on breaking the primary. With our ordinary 6 volt coil this current seems to be in the neighbourhood of 3 amperes. To make a finished piece of work it will be advisable to use the full 12 volts that we are using for the starter and lighting system, and I think it will be found to work remarkably well if a coil wound for 6 volts is supplied with 12 volts through a suitable non-inductive resistance as suggested above, but to avoid working in the dark it will be advisable to find out what proportion of the electro-motive force in the case of the Remy or Delco system is absorbed by the coil and what proportion is absorbed by the protecting resistance. It will be necessary to advance the contact maker on the battery ignition as now fitted to the car, so that this breaks the circuit much earlier, and when the high tension distributor has only just come opposite the contact, that is to say, the cam working the make and break will be advanced, nut not the distributor. It will also be necessary to alter the range of control, so that the battery ignition has the same lead and angular advance as the Contd. [Faint upside-down text in bottom right corner: H.R. 2512 (500 G) (S. 40S. 20-4-17) Bm. 2/85/13.] | ||