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).
Carburettor performance issues and development, focusing on fuel metering and potential leaks.
| Identifier | ExFiles\Box 13\3\ 03-page384 | |
| Date | 17th February 1932 guessed | |
| -2- Slow running operates quite well and covers the idling range up to 500 RPM. light running at which speed the diffuser definitely commences to supply fuel. Under full load conditions the small choke and diffuser supply the demand up to 650 RPM. when the air valve diaphragm starts to open. At the moment the metering is bad and we are attacking the problem in three stages. (1) Slow running by the throttle edge feed up to 500 RPM. (light running when the diffuser commences to operate. (2) The complete diffuser range up to where diaphragm commences to lift both under light and full load running and regarding it as a complete small carburetter. (3) Obtaining a suitably tapered needle to give a correct metering from the point of the diaphragm lifting up to full lift under all running conditions Some features which need attention are :- (a) Possibility of suction leaks past needle valve in its sleeve. (b) Leaks past the main jet in its guide. Trouble has been experienced in the air valve picking up in its guide, both of these parts being made of aluminium. Further development of the carburetter is being carried out with the suction to the piston blanked off and the small release to atmospheric using the piston merely as a dashpoty. At present we are working on the metering of the diffuser and loading up of petrol at low speeds full throttle in the large choke. Es/L.H.Swindall. | ||