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 results and required modifications for the Wraith III unit.
| Identifier | ExFiles\Box 6\6\ 06-page376 | |
| Date | 19th November 1937 | |
| To By/CS. from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}7/AP.19.11.37. WRAITH III. UNIT Preliminary tests have been carried out on an up-to-date unit built precisely to the latest LOP. The following points have shown up and we should like you to modify the details accordingly with the necessary alteration to the LOPs. for the 6 cars which RMC. is to build. (1) There is only a .010 clearance between the sides of the bottom tappets and the holes in the base of the cylinder block. More clearance should be given at this point as considerable damage might occur if the tappets fouled the sides of the holes. (2) The oil supply is rather on the lean side to the push rods which has been corrected by opening up the feed holes in the rockers from .031 dia. to .046 dia. Will you also include this modification to the Phantom III. solid rockers. (3) Due to the new position of the relief valve in accordance with E.C.D.62 the original Wraith relief valve springs were included on the LOP. being E.87825 High pressure and E.87831 Low pressure. These gave excessively high oil pressures and were corrected by fitting the springs E.88790 high pressure and Ex.28174 low pressure. Will you modify your LOPs. to include the latter springs. (4) We note that there is no limit given on the 45' angle of the boring of the crankcase for tilting the bottom tappets. No doubt production will require a limit in which case we recommend 45' -10'. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||