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).
Technical memorandum discussing empirical data and design requirements for Phantom II and 25 HP valve springs.
| Identifier | ExFiles\Box 179\2\ img167 | |
| Date | 21th January 1932 | |
| E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} c. to Ry. Wor.{Arthur Wormald - General Works Manager} ORIGINAL Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}1/MA.21. 1. 32. P.II VALVE SPRINGS. X290. We have the following empirical data to work on :- Camshaft. Rockers. Valve lift. Spring. lbs (valves open.) Speed of valve bounce. STD WW 114° STD .429 E.81550 106 3000 WW 114° STD .479 E.81550) E.37610) 150 3750 WW 114° High lift. .520 " 156 3400 With the inner spring we are using the asbestos washer cannot be used. We therefore require a design for double valve springs on the lines of that used on 10-EX, for the Continental P.II. To hold the tappet weighing .284 lbs onto the cam at 3750 r.p.m. requires a tappet spring of 26 lbs. The present spring gives 15 lbs. We have fitted to the 2.800 journal unit tappet springs giving 40 lbs. If we use high lift rockers on the Continental P.II we shall need a total poundage from the valve springs of about 170 lbs in conjunction with tappet springs that hold the tappet onto the cam, in order that the valves may not bounce below 3750 r.p.m. 25 HP VALVE SPRINGS. Camshaft. Valve springs. lbs Valve bounce. WW E.57177 Hs{Lord Ernest Hives - Chair} 451 86 3900 Two exhaust cams of E.57177 Hs{Lord Ernest Hives - Chair} 477 and stronger tappet springs (25 lbs) 79 4100 The tappet springs cannot be usefully stronger than 25 lbs. For the J.I. unit to run up to 4500 r.p.m. we require a valve spring to give 95 lbs. We can get this from pullin out the spring Hs{Lord Ernest Hives - Chair} 477 without stressing it above 75000. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||