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).
Investigating low-speed misfiring, considering reducing spark plug gaps and the impact on slow running quality.
| Identifier | ExFiles\Box 60\3\ Scan149 | |
| Date | 9th April 1932 | |
| 86095 To R.{Sir Henry Royce} From Hs.{Lord Ernest Hives - Chair} c. to E.{Mr Elliott - Chief Engineer} By.{R.W. Bailey - Chief Engineer} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to PN.{Mr Northey} CHASSIS BATTERY IGNITION. With reference to the attached. The mis-firing at low speeds has been difficult to locate. On the last 25 HP. car which was run in France, part of the routine test every day was to make a definite test for this phenomenon. Very occasionally it would occur but then without touching anything it would disappear. We hope it will not be necessary for us to reduce the plug gaps .015". This is a smaller gap than we have ever used on any of our cars, and it is smaller than any of the other makers use. The Standard gap fixed by the plug makers as the best compromise to suit all cars is .025". With the smaller gap we shall definitely have less reliable slow running. At the present time the makers of cars with fluid flywheels are emphasising the advantage the have in phenomenal slow running on top gear. Although we cannot hope to approach them, it would be unfortunate if we had to sacrifice our present slow running quality. Hs.{Lord Ernest Hives - Chair} | ||