Attempts to cure valve spring surge and valve bounce on the Vulture Automatic Tappet Cylinder Head.
| Identifier | ExFiles\Box 123\3\ scan0170 | |
| Date | 1st April 1934 | |
| X4704 April, 1934. Report on further attempts to cure trouble due to Valve Spring surge and Valve bounce on the Vulture(Experimental 6 CYL OHV LONG STROKE / Aero Engine) Automatic Tappet Cyl. Head. To cure this trouble it was decided to try the following - (1) Changing the present camshaft (standard E.82448) for the old standard one (E.80070). (2) Changing the valve springs as fitted to Vulture(Experimental 6 CYL OHV LONG STROKE / Aero Engine) head (E.84551 & E.84552) for a set of higher rating springs to Hs. {Lord Ernest Hives - Chair} 1302. Accordingly a camshaft to E.80070 was fitted to P.II No. 7 Engine Unit, and the Vulture(Experimental 6 CYL OHV LONG STROKE / Aero Engine) Cylinder head (fitted with springs to E.84551 & E.84552) fitted and run up to 3600 r.p.m. before any trouble was experienced - above this speed the trouble due to valve bounce began to be felt. The valve springs were then changed for springs to Hs. {Lord Ernest Hives - Chair} 1302 - these ran satisfactorily as far as we thought it safe to run the engine; i.e., 3700 r.p.m., without any signs of valve bounce. Owing to lack of time, this cylinder head being needed for 28-EX car, it was impossible to compare these springs with the present standard camshaft E.82448. Note: During the course of the tests, No. 3 Connecting Rod broke at 3600 r.p.m. Power curves showing the difference in max. power obtainable with the two camshafts (E.80070 - old standard; and E.82448 - latest standard), using present standard compression ratio, and carburetter on NO. 7 large bore unit, are attached. | ||
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).