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).
Analysis of ignition coil wiring configurations and earth systems to optimize output voltage.
| Identifier | ExFiles\Box 168a\4\ img140 | |
| Date | 13th December 1939 | |
| -2- (A) PRIM. SECONDARY PLUG CONTACT BREAKER (B) (C) (D) Tests have been taken by means of our H.T. voltmeter and the output voltage for the various arrangements taken. The following results were obtained :- As in (b) :- 8.50 K.V. " " (c) :- 8.95 K.V. " " (d) :- 9.2 K.V. Thus, we can, by modifying the arrangement of connections from (b) to (c) obtain a slight improvement on the std. R.R. coil, when working on a negative earth system, and a still further improvement by modifying from (b) to (d) if on a positive earth system. We may state, also, that with the present negative earth on the battery, we do not get the best performance from "bought out" coils, as those on the British Market are, in general, designed for a positive earth. The gain is not great, but it can mean the difference between good performance and misfires, when called upon to fire large plug gaps and/or weak mixtures. Most of the British cars have now reverted to a positive earth, and the electrical units are designed to work most efficiently this way, therefore, in the case of the small car, where we intend to use a number of "bought out" units, the positive side of the battery should be earthed. This incurrs some alteration in our present layout and design, but as in the case of the small car, we are starting from scratch, this should present no difficulties. Rm{William Robotham - Chief Engineer}/RC{R. Childs}: | ||