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).
Recurring exhaust valve failures on the 25/30 HP engine and recommending a cylinder head alteration.
| Identifier | ExFiles\Box 106\5\ scan0164 | |
| Date | 31th July 1936 | |
| To E.{Mr Elliott - Chief Engineer} c. to Sg.{Arthur F. Sidgreaves - MD} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} c. to Mx.{John H Maddocks - Chief Proving Officer} X534 Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}19/KW.31.7.36. 25/30 HP. Exhaust Valves. It will be remembered that the first half of the Standardisation Test on the big bore 20/25 engine was terminated by a valve head dropping into the cylinder (see memo. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}11/KW.10.4.36). The valve was strengthened up, which overcame the trouble, but in the course of the investigation we determined that on the new cylinder head the exhaust valve was running at a higher temperature than either the Bentley or the Phantom III. At the end of 13,000 miles on the strengthened valve Hancock reports sticking in the guides. Though we have cured the failure, the hot exhaust valve is still giving us trouble. We recommend that we should at once alter the 20/25 cylinder head so that the water, together with the exhaust valve guide, is brought down nearer to the valve seat. As will be seen from the attached report, we have proved that we can do this without loss of power. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Att: Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}1/KW.31.7.36. | ||