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).
Required modifications to compare the roughness of 20/25 HP and Bentley cylinder heads.
| Identifier | ExFiles\Box 103\4\ scan0117 | |
| Date | 28th May 1934 | |
| 5050 To RHC.{R. H. Coverley - Production Engineer} Hs{Lord Ernest Hives - Chair}/FJH.{Fred J. Hardy - Chief Dev. Engineer}3/KW.28.5.34. Experiments on the roughness of 20/25 HP. and Bentley Cyl. Heads. We wish to carry out on chassis 18-C-IV some tests to compare the roughness of the 20/25 HP. type cylinder head with the Bentley type. To do this we want :- (1) A 20/25 HP. type cylinder head which we will supply machined down at the base by 0.057 to raise the compression ratio to the present Bentley standard, also the valves of this head require grinding in. The stud holes in the induction and exhaust manifolds may have to be elongated to suit. (2) Longer holding down studs in the crankcase to suit a Bentley head. (3) A flanged joint placed in the downtake exhaust pipe immediately above the front expansion chamber and alternative downtake pipes made to suit the 20/25 head and the Bentley head. (4) The rubber engine suspension replaced by solid blocks. Will you please carry out the above work and at the same time give the unit (U.7.S.) a general overhaul. Hs{Lord Ernest Hives - Chair}/F.J.Hardy. | ||