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).
General conclusions on engine head development, covering gaskets, cooling, valves, and timing.
| Identifier | ExFiles\Box 134\2\ scan0146 | |
| Date | 23th August 1937 | |
| -8- Gaskets. Considerable trouble was experienced with leaky gaskets due to insufficient clearance between the combustion space and stud holes. C. & A.{Mr Adams} gaskets appeared the best. (a) GENERAL CONCLUSIONS TO DATE It is considered that this head has now been developed to the stage when a main engine could be proceeded with. The salient features appear to be:- (i) Adequate cooling between the block and the exhaust port, incorporating a cooling rail. Also the distance between the combustion space and the holding down studs should be kept as large as possible. (ii) Due to the critical nature of the exhaust port temperature siamesed ports might prove too hot and allowance in the design for a six port engine should be made if practicable. (iii) A cast iron block employing a 1.500" diam. solid exhaust valve appears satisfactory, only, however, if used in conjunction with the inclined valve head. (iv) Adequate throat area is essential, at least 1.500 sq/in. as this is the controlling factor for high speed detonation and ignition advance. (v) The inlet valve should be inclined to give : (a) Small volume for final period of combustion. (b) Suitable throat area. (c) Good proximity of plug points and inlet valve. (vi) Plug points should be as near as possible to the inlet valve, as this gives:- (a) Good burning of weak mixtures with consequent fuel economy. (b) Good burning at small throttle openings with resultant good tick over. (vii) Valve timing should have a short duration -210°- with no overlap. The exhaust timing should be approximately standard Bentley i.e. E.O. 50° BBDC, E.C. TDC. This takes into account the back pressure response. | ||