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).
Request to produce a set of six sodium-cooled Bentley exhaust valves to test their effect on engine pinking.
| Identifier | ExFiles\Box 88\4\ scan0151 | |
| Date | 7th December 1935 | |
| To RHC.{R. H. Coverley - Production Engineer} x254 HS{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}3/KW. 7.12.35. Salt Cooled Bentley Exhaust Valves. Various reliable authorities have stated that ordinary pinking on a car is much reduced if the temperature of the exhaust valves is lowered. We are of course always more or less in trouble with pinking on the Bentley. To prove out this point will you please make us a set of six sodium cooled Bentley exhaust valves. We should like these valves to be as fully cooled as possible without making them very costly. We shall not run endurance on them, so that if they are as strong as the drilled SpectreCodename for Phantom III exhaust valves which failed previously, this will be quite satisfactory for our purpose. If you want to put a larger hole in the stem, then it may be necessary to go to the increased size of the SpectreCodename for Phantom III, but we should like to avoid this as it will affect their interchangeability and will mean a special valve guide. HS{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||