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).
Specifications and test procedures for Wraith III engine units No. 10 and No. 4.
| Identifier | ExFiles\Box 155\2\ scan0324 | |
| Date | 25th May 1939 | |
| -2- Rm{William Robotham - Chief Engineer}/Swd1.8/WH.25.5.39. (5) Unit generally to be brought up to standard for fitting in car in respect of slow running, leaks gears and valve gear. Wraith III No.10 Unit (Continental). Unit for above 14.B.V. chassis. Special features include - (a) 3 layer main bearings (Vandervell). (b) L 5 alloy crankcase. (c) Camshaft (Monikrome running direct in crankcase. (d) .470 raised crown piston with 2 - .030 gaskets under cylinder head 7.75 : 1 C.R. (e) Coolant jet scheme. (f) Strengthened exhaust valves and shot blasted valve springs. After running in check tests as specified for B.80 No.4. unit with exception of following - (1) Detonation curves etc. and governor characteristic to suit Shell No.1 not Redline (2) With silencer check valve bounce. (3) Carry out tests on coolant jets similar to carried out previously on Wraith III No.4 unit with rad. in position. (a) Temperatures along both sides of cylinder head with an outlet temp. of 80°C. (b) Venturi flow reading together with inlet and outlet temperatures. (c) Switching off tests and time to stop. (d) Valve temperatures on weakest maintained. Wraith III No.4. Unit. Prior to running endurance as specified in previous | ||