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).
Modification of Wraith cylinder heads and valves, including comparisons to Phantom III components.
| Identifier | ExFiles\Box 8\6\ 06-page32 | |
| Date | 31th May 1938 | |
| To HPS.{Horace Percy Smith - Experimental Factory Mgr} 649? Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}11/JH,31.5.38. WRAITH CYLINDER HEADS. -6524 or 7360 In connection with the valve seat warping job we are by stages gradually bringing back the original small valve head EX.29685 up to standard in order to obtain direct comparisons with regard to power. Will you please follow up by producing another small valve head EX.29685. Regarding the valves the exhaust EX.29687 are available likewise the inlet valves EX.29686. The inlet valves were copied from the Phantom III type of tulip valve and in order to compare we would like you to produce 6 inlet valves from the existing standard inlet valve Ex.1429, i.e. machine down from 1.6 to 1.5 diameter. Will you please urge the above job as the results are required for production. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||