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).
Short duration camshaft with large tappet clearances for the Phantom III engine.
| Identifier | ExFiles\Box 93\5\ scan0042 | |
| Date | 4th December 1936 | |
| Files eur 309 To BY.{R.W. Bailey - Chief Engineer} Copy to Ds. Rm.{William Robotham - Chief Engineer} Hives 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 seats 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. Handwritten note: From Camshafts that have recently been made, can you tell me how long Att:LEC.5401.. this is likely to be. Can we make sure the forms are made by the people who work most rapidly | ||