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).
Carburetter issues, particularly sticking air valves, and a specification for a new carburetter design.
| Identifier | ExFiles\Box 179\3\ img086 | |
| Date | 19th March 1932 | |
| -2- In the original piston having no centre guide but taking its bearing on the side of the piston, we experienced trouble by sticking and careful attention to the bearing surface was necessary for it to operate correctly. The sticking of the air valve is a common trouble on the present Phantom carburetter and from our experience the use of a steel centre guide relieves us of much of this trouble. Since the carburetter is beginning to take a fixed form we intend to proceed with the metering as we originally laid out in three parts. (a) Slow running by throttle edge scheme. (b) Treating the diffuser and small choke as a complete carburetter and correctly metering it up to the speed where the suction piston starts to lift and for all conditions of loading. (c) To obtain a correct needle valve form which will suit all positions of the suction piston when running under light and heavy loads. We should like another carburetter built to the following specification. (1) Slow running. The fuel feed to the slow running jet be taken from the diffuser base in a position similar to that used on the Aero-carbs in the Vees. Present fuel hole from float chamber to slow running to be blanked up. (2) Petrol passages. (a) Main petrol supply passage from the float chamber be increased from .213 dia to .265 dia. (b) Three feed holes in carburetter Body casting (X. 83711) increased to six of the same diameter. (c) The dowel pin collar on (E.{Mr Elliott - Chief Engineer} 82854) main jet guide to be deleted and located to prevent turning in another way, say small dowel pin on the top face. (d) The six inclined holes through the main jet guide increased from .089 to .109. | ||