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).
Valve seat failures on Wraith cylinder heads after various mileage and test bed conditions.
| Identifier | ExFiles\Box 10\3\ 03-page183 | |
| Date | 1st October 1938 | |
| Rm.{William Robotham - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} Rm{William Robotham - Chief Engineer}/Swd16/R.1.10.38. VALVE SEAT FAILURES ON WRAITH. We attach herewith a list of the cylinder heads examined. CHASSIS (original type large valves). (1) WXA1 (Sg{Arthur F. Sidgreaves - MD}'s car) No cracks after 10,254 miles. (2) WXAL8 (Rs{Sir Henry Royce's Secretary}' Car) " " " 13,200 " (3) 24.G.VI. " " " 26,000 " (4) 25.G.VI. " " " 10,700 " (5) 28.G.VI. " " " 12,000 " This car has been used on numerous tests in the cold chamber. (6) 29.G.VI. No cracks after 10,000 miles. Test Bed (original type large valves). (1) After series of cycles starting from cold, running at high speed, then cooling down again, Nos. 2, 3, 4 and 5 cylinder exhaust seats cracked. (2) After 200 hours development on test bed, also including some mileage on 27.G.VI, slight cracks in two exhaust seats. (3) No cracks after 250 hours' running on test bed. (4) No cracks after 40 hours' endurance running at high speeds. CHASSIS (Present standard small valves). (1) 27.G.VI. Slight cracks on Nos. 2 and 5 exhaust seats after 6,500 miles. The following chassis have recently been fitted with small valve heads and not since examined. | ||