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).
Specifications for engine components including pistons, cylinders, and valves.
| Identifier | ExFiles\Box 97\1\ scan0217 | |
| Date | 17th September 1938 | |
| -2- Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}4/MH.{M. Huckerby}17.9.38. Pistons. Aerolite, as present production Bentley, but with raised crown to Rm.{William Robotham - Chief Engineer}522. The object of this is to enable use of 6.5 : 1 Comp. ratio on Bentley against 6.0 : 1 on the Wraith, yet both engines having the same cylinder head. Cylinders. (1) Up to date Wraith cylinder block EW.1580, likewise cylinder head EW.1854 (small valves). (2) Cylinder head to include inclined push rods ECD.775. (3) Both block and head to include modified coring ECD.871. (4) Klingerit cylinder head gasket as per our memo Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}18/JH.15.9.38. (5) Hot die pressed brass rocker cover nuts nickel plated. See RHC{R. H. Coverley - Production Engineer}/SB.{Mr Bull/Mr Bannister} for particulars of these. (6) Neuprene rubbers in place of springs under rocker nuts. The details of these rubbers are - Outside dia. .875 Bore of hole .500 Thickness .450 Durometer hardness of 70. (7) Gaskoid rocker cover joint. Valves and Fittings. As up-to-date Wraith incorporating:- (1) .4 Carbon steel push rods as supplied by the Belgrave Eng. Co. Machined only at the spherical ends. Heat treated at the ends. Continued. | ||