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).
Development of the induction system and carburettors for the 3.500 Bore Bentley.
| Identifier | ExFiles\Box 85\4\ scan0132 | |
| Date | 18th September 1935 | |
| To Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} c. to Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} X208 Hs{Lord Ernest Hives - Chair}/CTS.{C. Trot Salt - Carburation}3/KW.18.9.35. 3.500 Bore Bentley - Induction System. Induction Pipe Required. Ex.19087/6 modified as follows :- Overhang past the end cylinders (buffer ends) increased to 1.00". Further development necessary: Investigate possibilities of reducing the heat on this pipe, as at least 5% of power drop exists at present (mid. speed M.E.P.). Carburetters required. 1 3/4 S.U. type H.V.5. The outstanding fault on these carburetters is the fact that the float chamber needle valve can jam open. The overall length of this carburetter is .325 longer than the present standard 1 1/2 S.U. carb. on the 3 1/2 litre Bentley (EB.200). One pair of 1 3/4 carburetters have been tested on the test bed, modified as follows :- The dimension between the main jet and throttle spindle decreased by .500. Result. No adverse effect is in any way appreciable. Road tests are necessary to further establish this point. Further development necessary. Metering (needles). These are controlled by the air silencer, which has not yet been produced. Adjustment of piston weight, if found necessary from road performance (pick up). Finally, these carbs. should be re-designed to incorporate improved float chamber mechanism. petrol drains and overflow pipes, and general improvements, as carried out on the 1 1/2 S.U. carbs., and shown on EB.200. | ||