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).
Comparison of three valve head designs and a discussion on valve timing for competition cars.
| Identifier | ExFiles\Box 133\2\ scan0097 | |
| Date | 15th November 1934 | |
| -2- Fig. 1. Fig. 2. Fig. 3. Each of these forms gives the same clearance between the wall and the valve head at maximum lift, but whereas Fig. 1 allows more anular space around the valve at small lifts, the streamlining is much worse than in Fig. 2. It would be very useful to know the relative importance of these two factors. We are not clear regarding the actual timing which gave the maximum peak power with the ramp head (chain line, sheet 4). Does this timing give a similar increase in high speed power on a standard head ? If so it may be well worth while to have a multi-cylinder camshaft made to this timing for development work on competition cars. We suggest that some useful information could be obtained from a detailed research into valve timing. We appreciate that single cylinder experiments in this connection are not directly applicable to multi-cylinder engines, but they would provide some indication of what results we might expect. We note, for instance, that E.R.A's on a supercharged engine use 96° overlap with .008 to .010 clearance, the exhaust valve opening 45° early. It would be interesting to know how our engine behaves with a similar timing. | ||