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 valve springs and a detailed description of the camshaft assembly and its operation.
| Identifier | ExFiles\Box 23\5\ Scan032 | |
| Date | 20th December 1927 guessed | |
| -4- contd :- Free length = 2.843" Dia. of wire = .190" 9 working coils, 2 half coils, one at each end ground square. Inside dia. top = .8719" bottom = 1.015" Load for .500" deflection = 68 lbs., which gives the actual rating as 136 lbs/in. considerably higher than the figure given by Stutz. The weights of the various valve parts are given together with the other engine weights. CAMSHAFT. The camshaft is carried on the cyl. head vertically above the valves; the cams wipe directly on the caps. There are five camshaft bearings which consist of bronze pedestals mounted on the cyl. head, the bearings being the pedestals themselves. The front bearing is 1.57" long and 2.375" wide and also takes the end thrust, the remaining four bearings are 1.50" in dia., and 1.312" in length. The camshaft is made of McQuade-Ehn S.A.E. No.1015 forging steel, case carburized and hardened. The cams are of the mushroom type working directly on the valve caps. The cam base circle is 1.650" in dia. Fig.11 indicates the valve opening diagram obtained, also the valve timing used. A running valve clearance of .028" is recommended. The inlet and exhaust cams are identical in contour, and the exhaust cam leads its inlet cam by 116°. The camshaft driving sprocket is bolted to the front end of the camshaft by four screws and rotates in the same direction as the crankshaft. Pressure oil is fed to the hollow camshaft distributed to the bearings and also to the 'cam heels'. Each cam is fitted with an oil metering pin (illustrated in fig.1.) which wipes on the valve cap leaving a trail of oil behind it so that there is always an oil cushion maintained between the valve cap and the cam. contd :- | ||