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).
Recommendations for the Bentley III cylinder head design and testing.
| Identifier | ExFiles\Box 99\1\ scan0110 | |
| Date | 11th October 1937 | |
| SECRET Hy.{Tom Haldenby - Plant Engineer} from Rm.{William Robotham - Chief Engineer} O.{Mr Oldham} Da.{Bernard Day - Chassis Design} O.{Mr Oldham} HPS.{Horace Percy Smith - Experimental Factory Mgr} BENTLEY III. CYLINDER HEAD. We recommend that we instruct standard Wraith cylinder heads to be manufactured for the first three Bentley IIIs. These will of course be instructed with the Bentley induction system. We can get the necessary compression ratio for test purposes by using thin gaskets. We think that the final Bentley III. cylinder head should wait for the result of the tests on the Buick type of combustion chamber. The other feature which we know would be advantageous, is to be able to separate the two blocks of three cylinders with reference to their exhaust system. We believe it is worthwhile looking into this matter, even if it means reverting to the 6 port inlet cylinder head at present fitted to O.B.IV. It must be remembered that we do not expect to get any better results from the 4 port head than the 6 port we have used in the past. Also the 25/30. and Bentley cylinder heads have never been interchangeable as they have not the same compression ratio. Rm.{William Robotham - Chief Engineer} | ||