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).
List of specifications and modifications for various Wraith II and Wraith III engine units.
| Identifier | ExFiles\Box 155\2\ scan0198 | |
| Date | 7th February 1938 | |
| -2- Wraith II No.2 Unit (25.G.VI). As No.1 unit but with - W/M.{Mr Moon / Mr Moore} main bearings with RR.56 solid shims. Hall's metal big ends with RR.56 shims. Swedish wire valve springs. - 1 - 6 Rm.{William Robotham - Chief Engineer}260 made by Tempered Spring Co. 7 -12 EB.3256 coiled by R.R. 2 inlet cam camshaft ex C.15 unit Ex.24268. Holes in end of rockers plugged. Wraith III No.1 Unit (Rig engine pistons tests). W/Mt. main bearings RR.56 liners. (N.4.7 new after 7000 miles) Crankshaft with 2 - .125 holes in pins. A.C.6 big ends single hole feed in bush (top half) Ex.28171) Unhardened engine gears in S/ZNX. Bottom tappets in I/C (R.R.) Chevrolet type Ex.27980 with push rods to suit. Tappet guides tilted by boring 45'. Annulus in front and rear bush of spring drive to improve lubrication of 'cotton ducks'. KE.965 stell. exh. valves 1.4 dia. } Improved core cyl. head S.85 inlet valves 1.6 dia. } LeC.5084 New after 7000 miles. Nos. 1 - 6 valve springs S/CV. (RS.{Sir Henry Royce's Secretary}540) Blue Nos. 7 -12 " " (Swedish w.re) Red and Blue increased heat treat) RR. coiled. RS.{Sir Henry Royce's Secretary}540. Rm.{William Robotham - Chief Engineer}400 top spring washers. Relief valve springs L.88790 main. Ex.28174 rocker. Lower rated spring drive friction springs. Ex.28254 springs. Rm.{William Robotham - Chief Engineer}402 caps. Set at 15 - 17 lbs. at 17 1/2" rad. Lucas suction ignition control. Wraith III No.2 (Valve endurance). W/M main brgs. RR.56 shims (Grooved and drained rear main). AC.6 big ends thin section. 1, 3 & 5 flanged, 2, 4 & 6 non flanged. Unhardened engine gears S/ZNX. Up-to-date cylinder head and valve gear. 6' grummets to give correct spring length. 1 - 6 EB.3256 valve springs 7 - 12 Ew.1428 springs S/CV. Loose liner cylinder block. 5/16 dia. push rods. cont'd.{John DeLooze - Company Secretary} | ||