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 report on Phantom III valve gear, comparing a small base circle camshaft with different tappet materials.
| Identifier | ExFiles\Box 96\2\ scan0222 | |
| Date | 26th April 1937 | |
| To E.{Mr Elliott - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} c. to RHC.{R. H. Coverley - Production Engineer} c. to By.{R.W. Bailey - Chief Engineer} c. to HPS.{Horace Percy Smith - Experimental Factory Mgr} Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}1/AP.26.4.37 354 PHANTOM III. VALVE GEAR. We have tested the small base circle camshaft (LeC.5320 - .950 dia.) in order to see if the reduced rubbing speed between the camshaft and the tappets gave any improvement with regard to wear on the face of the tappets. Nos.1, 2 & 3 tappet blocks had tappets in S/ZN. with a cloudburst hardened face and Nos.4, 5 & 6 with a standard Fescolised face. After one hour endurance at speeds between 4000 and 4500 R.P.M. they were removed and it was found that the cloudburst tappets had started grooving, this in some cases being to the extent of .050 wide and right across the face, whilst the standard Fescol tappets were in good condition. From previous tests we consider that the result is no better than obtained on a standard camshaft (1.250 dia.) running with similar cloudburst hardened tappets and at higher rubbing speeds. In consequence there is no point in carrying out any further tests on the small base circle camshaft, the main object in trying this being to see if it was possible by the reduced rubbing speed to be able to replace Fescolised tappets by a case hardened tappet. In conjunction with the standard camshaft which has been tried Fescolised, cast iron tappets have been tried, running with and without the hydraulic tappet mechanism, likewise the bottom springs, but in all cases, we have not up to the present had any type of tappet that approaches the standard of Fescolised tappets. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||