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).
Description of the general construction and petrol flow within the carburetter.
| Identifier | ExFiles\Box 13\4\ 04-page038 | |
| Date | 21th September 1932 | |
| -5- Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}12/KT.21.9.32. General Construction of the Carburetter. Petrol is fed from the floatchamber via .255 diameter hole in the carburetter casting, into a well below the main jet mechanism, thence upwards through 6 holes in the casting (.155 diameter). From here it passes through 9 (.089 diameter) holes and a further 6 (.109 diameter) holes in the main jet guide. In this position there is a depression which takes the petrol through the orifice between the taper needle valve and the main jet. From the inside of the main jet it passes through 4 (.105) holes, which are in line with a passage .213 diameter, leading to the base of the diffuser, through which it is delivered into the small fixed choke. The slow running petrol feed is taken from the base of the diffuser by .213 diameter passage in the carburetter casting, and thence through a fine mesh filter into a well below the slow running jet, the latter having .031 diameter feed hole. Further passages include - (a) Mixture feed from the slow running unit to the throttle edge plug. (b) Air bleed passage from the air intake to the slow running unit. (c) Air vent from the air intake to the floatchamber. The passages and various size holes must be drilled strictly to drawing and burrs removed. When the suction is sufficient to lift the suction piston, air is admitted into the large choke. The taper needle also is lifted, increasing the orifice between the taper and the main jet, and thence the fuel is delivered through the diffuser. The whole of the fuel supply is taken through the diffuser in the small choke air only, passing through the large choke. The inside of the carburetter casting should have all sharp edges removed to avoid whistling in the intake. Hs{Lord Ernest Hives - Chair}/L.H.Swindall. | ||