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).
Issues and operational principles of the EAC carburetter for the 40/50 HP engine.
| Identifier | ExFiles\Box 66a\1\ scan0018 | |
| Date | 1st January 1925 | |
| R.R. 493A (50H) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. -4- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/ACL/LG15.1.25. 40/50 HP. Suggested reasons for the troubles, stated above, arising with the EAC. carburetter. We may take the following facts as the basis of operation of this type of carburetter. From consideration of the effect of throat size, spring rating and port shape we may say :- (1) That for each size of throat there is a particular combination of spring rating and air port shape which must be used to give a correct mixture over its range of action - that is, for the carburetter to be automatic. (2) There is a particular maximum power output which can be obtained from a given throat assuming of course that each throat is used in conjunction with its correct combination of spring rating and port shape. To simplify explanation, we will split up the action of the carburetter into two parts - Phase 1. and Phase 11. Where Phase 1. deals with the action up to the point at which the high speed jet comes into operation, and Phase 11. the action after the high speed jet has started. Now considering the reasons for trouble arising with the EAC. carburetter :- The 40/50 carburetter on the EAC. engine gives the same metering through both Phase 1. and 11. as it does on the 40/50 HP. Although the EAC. engine is only about 3% larger than the 40/50 HP., its greater power output is chiefly due to its greater volumetric efficiency which means that in contd :- | ||