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).
Page detailing possible troubles from incorrect carburetter settings and explaining the automatic range of the carburetter.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan191 | |
| Date | 29th January 1925 guessed | |
| contd :- -6- POSSIBLE TROUBLES CAUSED BY INCORRECT SETTING. It is quite possible for trouble to occur through the incorrect setting of the low speed jet with relation to the engine speed and lift of the air valve, and may happen in one of the following ways :- (1) The low speed jet may be adjusted to give a correct mixture at a speed below that at which the air valve starts to lift and in this event the mixture will be correct at that particular speed only. (2) May be set when the air valve starts to lift but owing to the diaphragm being fixed too low down at it will require a certain lift of the air valve and consequently an increase of speed, before air can be admitted through the diaphragm ports. Probably these are two of the most common causes of a non-proportional mixture at low speeds and light loads and the symptoms are excessive rich spots which give rise to unsteady running. AUTOMATIC RANGE OF CARBURETTER. The chief point to remember is that the carburetter is designed to be automatic over a certain range and that range is from the time the air valve starts to admit air through the diaphragm ports until it attains its maximum lift. At a speed below that at which the air valve starts to lift the carburetter is not automatic and the mixture will become rapidly weaker as the speed decreases. At such low speeds it will therefore be necessary to revert contd :- | ||