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).
Test specifications for Wraith III and Wraith II engine units, detailing modifications and running procedures.
| Identifier | ExFiles\Box 155\2\ scan0203 | |
| Date | 2nd March 1938 | |
| -2- WRAITH III NO. 1 UNIT. This unit has been fitted with special arrangement of bottom tappets, all are vertical with flat base. 1 - 4 As original Wraith. 5 - 8 Front face of cam in line with C/L of tappet. 9 -12 Cam width reduced to .250 and is in effect similar moment of rotation as existing inclined tappet mechanism. Tappets to be noted for rotation and examined after say, 1 hour light running. If O.K. run 1 hour at Wraith endurance speed 4000, 4200 and 4400 then remove and return to shop. Include a check of valve bounce speed. No.2 unit to be refitted with Torsional indicator and if working satisfactorily will make a programme of tests desired. NO. 5 (RIG ENGINE) Rm{William Robotham - Chief Engineer}/Mths.{Reg Matthews} WRAITH II NO.1. Unit fitted specially for "scuffing" tests with new cylinder block and pistons. No.1, 3 and 5 std. pistons. No.2, 4 and 6 tin plated. In order to get a comparison would run in on thin oil and examine say, after 1 hour's running. Further tests to be carried out dependent upon condition of pistons including starting and stopping tests and some full power. | ||