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).
Road test report on engine misfiring and ignition performance under varied battery voltages on chassis 12-EX and 11-G3.
| Identifier | ExFiles\Box 168a\5\ img021 | |
| Date | 1st September 1927 | |
| Contd. -2- EFC5/T1.9.27. On chassis 12-EX the test was carried out on the road with only five cells of the battery connected to the electrical system, and with the dynamo and magneto permanently switched out of action, the contact points being of tungsten, and the available voltage being approximately 10.0. With conditions as above described, the engine, with an average load, was run up to speeds in the neighbourhood of 3000 r.p.m. without noticeable misfiring occurring. The battery voltage was then reduced to 8, when misfiring occurred at all engine speeds above 2800 r.p.m. At very slow speeds of the car, i.e. 4 to 6 m.p.h., still on 8 volts, the ignition functioned satisfactorily, although a slight improvement was noted in the acceleration when the voltage was again restored to 10 volts or to normal. On chassis 11-G3, in which case platinum points were fitted, a similar test was carried out. The engine with an average load was run up to speeds of about 3100 r.p.m. without noticeable misfiring occurring on 10 volts. The battery voltage was then reduced to 8 when misfiring at all engine speeds above 2100 occurred. The car was also run (still on 8 volts) very slowly and appeared quite O.K., although as previously experienced, acceleration was not quite as good as with 10 volts or normal supply, presumably due to the extra compression causing misfires when the throttle is opened. We are of the opinion, as a total result of all the tests described above, that the double ballast resistance is suitable for standardisation and accordingly we are issuing a standardisation sheet for this item. The particulars are as follows :- | ||