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).
Modifications for a special Bentley cylinder head for competition work.
| Identifier | ExFiles\Box 90a\2\ Scan114 | |
| Date | 13th July 1934 | |
| 9 To RHC.{R. H. Coverley - Production Engineer} From Hs{Lord Ernest Hives - Chair}/CTS.{C. Trot Salt - Carburation} X7962 Hs{Lord Ernest Hives - Chair}/CTS.{C. Trot Salt - Carburation}1/MJ.13.7.34. BENTLEY. SPECIAL CYLINDER HEAD FOR COMPETITION WORK. "We have just tried a cylinder head having a compression ratio of 7.75:1. This was tested with a special fuel, and has given very promising results. As we find that a much higher compression ratio can be used on the Bentley with very little detonation, we think that the next stage should be tried, as the resultant gain my be valuable. Will you please produce a head as follows - Cyl. Head. EB.1237. Cast iron modified as follows - Ceiling .200 lower. Complete set of valves .200 longer to suit, combining the latest scheme for preventing valves dropping into cylinders. Valves seats machined straight into head (no inserts). Radius round inlet seat to be machined away as on previous head. Finally .100 to be machined off the joint face. Single type rocker shaft. This will necessitate a single centre stud being fitted, and modification to centre pedestal for oil feed. Final capacity should be 72 cc's = 8.7:1 Comp. Ratio. Hs{Lord Ernest Hives - Chair}/C.T.Salt. | ||