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 procedures for a Wraith III unit with vibration issues and a B.60 unit with modified pistons.
| Identifier | ExFiles\Box 155\2\ scan0286 | |
| Date | 11th January 1939 | |
| -3- Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}1/MH.{M. Huckerby}11.1.39. WRAITH III NO.9 UNIT. This unit was removed from 1.B.50 on account of bad vibration which had all symptoms of broken crank or damper. Inspection has revealed nothing definite to account for this. When unit is assembled, run on bed and try to find whether this vibration is still in existence. F.Hallam knows it and heard it whilst in chassis. If absent check engine for power and quietness and pass off. NO.5 TEST HOUSE. B.60 NO.1 UNIT. (a) Try raised crown pistons with .100 machined off top of pump in conjunction with 6.25 head enlarged throat giving a comp. ratio of 6.8 : 1. (b) Try flat topped pistons which come flush with top of cylinder block and not .030 down as standard. These pistons to be tried with head of conditions (a) giving a comp. ratio of 6.4 : 1. (c) If pistons (b) are an improvement fit non sodium filled exhaust valves solid. Above to be tested as follows:- (a) MEP - Ignition loops on Redline. (b) Max. power open exhaust. (c) Switching off from 3000 R.P.M. also after shutting down to idling. Following above start endurance as specified in our previous memo Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}2/MH.{M. Huckerby}24.11.38. Run normal daily work time, 8 am. to 5-30 pm. | ||