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).
Experiments and tests on battery ignition systems, comparing different components like contact points, coils, and condensers.
| Identifier | WestWitteringFiles\Q\December1926-January1927\ 114 | |
| Date | 27th January 1927 | |
| To R.H. from EFC. c.c. to E.W.H., B.J. C. to W.O.B., - B.Y. ORIGINAL EFC5/T27.1.27. X8680 X2894 X4652 BATTERY IGNITION. Your reference R2/M22.1.27. Tungsten contact points on our own ignition are, as suggested, nearly but not quite as good as platinum. Several have run 10,000 miles on the bench test without causing misfiring, though subsequent condition was not all that could be hoped for. Two sets have run 10,000 miles tolerably well on cars. (1) We are going to run tungsten on the ignition system on the 20 HP. 10,000 mile car IO-GIII, with the up-to-date finer primary coil, and double ballast resistance. If the result is reasonably satisfactory a standardisation sheet will be issued on the score of less expense. (2)&(6) Primary winding has been made finer (now standardised) to the degree we consider allowable. Ballast resistance of double value is hoped may be standardisable on result of 10,000 mile test referred to. With this arrangement it has been proved that engine will run to 2750 r.p.m. without misfiring at 10 volts but not on 8 volts. X8693 (3) The suggestion of quicker break and slower make will be experimented upon on the new lever now being detailed by the D.O. with off-set rubbing block. (4) Rigidity of lever is thought by ourselves and E.{Mr Elliott - Chief Engineer} not to be unsatisfactory in present form. Bouncing of contacts has been and will be further investigated by through observing loss of average current delivered to make and break to pure (non-inductive) resistance at varying speeds. No serious drop of this average current results running at a high speed. Comparison will be made of Delco-Remy in this respect by similar test. A further curve will be obtained with present standard spring and with spring of higher rating, when available. (5) Condenser has remained of same capacity when primary winding of coil has been made finer, and thus is virtually of larger capacity. A recent test with double condenser has not shown improvement, but test will be repeated. Points on Delco-Remy do not have or appear to require larger condenser. The most hopeful proposal not yet properly tried out would seem to be larger pressure on points. Contd. | ||