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 for the Wraith III valve lift curve, modifying the cam base circle diameter.
| Identifier | ExFiles\Box 10\3\ 03-page015 | |
| Date | 3rd March 1937 | |
| SECRET. 654 To-BY.{R.W. Bailey - Chief Engineer} Copy to Ber. HPS.{Horace Percy Smith - Experimental Factory Mgr} Hm.{Capt. W. Hallam - Head Repairs} Rny/Swdl.{Len H. Swindell} E/PSN.1/MN.3.3.37. [Signature] WRAITH III. Valve Lift Curve - LeC.5546. We send you herewith the scheme for the inlet and Exhaust Valve lift curve, LeC.5546, for Wraith III. This curve has a duration of 220° with .020" clearance and is intended to be used with flat tappets and a .275" cam lift. As the long-toed cams have not yet been tested the opening and closing toes have been made similar to the 25/30. The cam base circle diameter is to be 1.000" not .950" as specified on LeC.5543 which is hereby modified. This also requires a reduction of .025" in the push-rod length. Att:LeC.5546. E/PSN. | ||