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).
Suggested dimensions for a further set of experimental 3½ Litre Bentley pistons.
| Identifier | ExFiles\Box 86\2\ scan0062 | |
| Date | 7th September 1933 | |
| Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer} from Mx.{John H Maddocks - Chief Proving Officer} Mx{John H Maddocks - Chief Proving Officer}14/T7.9.33. 3½ LITRE BENTLEY - PISTONS. I am returning to you herewith your Blue Print with my suggested dimensions for a further set of Experimental Pistons. The differences between these dimensions and narrow bedded pistons which you have already run are - (1) The top load diameter decreased by .004" (2) The bottom load diameter decreased by .003" (3) The width of bedding at the bottom of the piston is increased by .250". This latter dimension is the one which is normally given by the increased length. (4) The diameters of land are the same as the present 20/25HP Pistons The amount of shrinkage lead for gudgeon pin is .0005" with small hole drilled in gudgeon pin bosses for lubrication. The piston dimensions given are grinding dimensions before splitting. The load dimensions at the bottom of the piston will increase by .002" after splitting and running. MX{John H Maddocks - Chief Proving Officer} | ||