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).
Phantom III short duration camshaft for running with large tappet clearances.
| Identifier | ExFiles\Box 96\2\ scan0175 | |
| Date | 4th December 1936 | |
| 354 To BY.{R.W. Bailey - Chief Engineer} Copy to Ba. Rm.{William Robotham - Chief Engineer} MX.{John H Maddocks - Chief Proving Officer} RHC.{R. H. Coverley - Production Engineer} Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} ------------------ Phantom III Short Duration Camshaft for Running with Large Tappet Clearances. ---------------------------------------------------- We send you herewith LeC.5401 of a short duration valve lift curve with long camshaft toes for use without hydraulic tappets and for running with large tappet clearances. The object of the short duration is to increase the low speed power. The object of having the long toes and large tappet clearances is to safeguard against any possibility of the exhaust valves being held off their seals under flat out conditions without any sacrifice of silence. Both inlet and exhaust tappets should be set to the same clearance which should be as large as possible compatible with silent operation to reduce effective over-lap and its detrimental effect on slow running. A clearance of .012" should be quite satisfactory and it might be possible to run with .014". Care will have to be taken when setting the tappets to ensure that the tappet is right off the toe of the cam and the engine should be rotated well past the apparent valve closing point before setting the tappets. E/PSN. Att:LEC.5401. | ||