Test bed programme for the Wraith III No.5 Unit, detailing special parts and performance checks.
| Identifier | ExFiles\Box 155\2\ scan0125 | |
| Date | 18th August 1937 | |
| To Rm. {William Robotham - Chief Engineer} c.c. to Rm {William Robotham - Chief Engineer} /Mths. {Reg Matthews} c.c. to Rm {William Robotham - Chief Engineer} /OTS. c.c. to Rm {William Robotham - Chief Engineer} /Ed. {J. L. Edwards} Rm {William Robotham - Chief Engineer} /Swdl. {Len H. Swindell} 15/JH.18.8.37. Programme of test bed work. Further to our memo. Rm {William Robotham - Chief Engineer} /Swdl. {Len H. Swindell} 12/AP.3.8.37. No.30 Bed. Wraith III No.5. Unit. Unit to be tested in preparation for fitting in chassis. Following special parts are fitted. (1) Vauxhall camshaft RS. {Sir Henry Royce's Secretary} 608 (.325 valve lift) to be timed with .030 clearance. (2) Bottom tappets with conical housing for push rods and external spiral oil groove deleted. (3) Higher helix angle timing gears, (4) R.R. distributor. (5) General filter, disconnect for test bed. Following the usual running in check (a) Power curve open exhaust. (b) " " with standard 30 H.P. silencer } up to 4500. (c) Maximum tappet clearances at which tappets remain quiet. Theoretically inlets should be quiet at .013 and exhausts at .020. (d) With the maximum for quietness setting check idling. Does idling improve with further increasing the clearances. (e) Is the valve mechanism more free from the periods experienced on Wraith. (f) At what speed do the valve bounce? try up to 4500 r.p.m. | ||
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).