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).
Carburetor issues, including sticking air valves and a comparison of materials and designs.
| Identifier | ExFiles\Box 121\3\ scan0091 | |
| Date | 14th November 1940 | |
| Rm{William Robotham - Chief Engineer}/OTS.6/SP.{Mr Spinney}14.11.40. - 3 - throttle bore of . This has now been completed but does not work well enough for S.U.s to wish to let it out of their factory. Instead of scaling up the small model, they attempted to reduce the comparative height of the larger model, and in consequence, the result is as already stated. 4. Sticking Air Valves (H.4. Carb.) - We acquainted them with this trouble and, as usual, they were amazed. Nothing was settled concerning the problem, however, and we have since given the matter further consideration. On the drawings attached, of the larger carburettor, it will be noted that the dash pot is secured by four lugs instead of two on the H.4 model. We suggest that we should get them to apply this principle to the latter, and are consequently proceeding to persuade them. We would justify this by the following facts:- a.{Mr Adams} The previous type of carburettor (S.U.) model H.V.5, had an aluminium cast body, with two lugs, and gave little if any of this trouble (M.{Mr Moon / Mr Moore} series Bentley). b. The H.4 is die cast in Zinc base alloy, of thinner section, and we know that this material wanders when warmed, e.g. The Stromberg body had to be trued up by skinning on the intake end, due to distortion after enamelling. The effect of this fault had been to cause sticking chokes. We therefore recognise this as the same breed of fault, and will persuade S.U.s to strengthen the lugs at the same time as increasing their number. Rm{William Robotham - Chief Engineer}/OTS. | ||