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).
Valve spring loads, performance, noise, and exhaust valve expansion.
| Identifier | ExFiles\Box 113\5\ scan0184 | |
| Date | 28th January 1937 guessed | |
| -2- VALVE SPRING LOADS. O.H.C. Limit. Valve Closed. Valve Open. RS.{Sir Henry Royce's Secretary}208 Inner } Inlet. 25 lbs 58.2 lbs. RS.{Sir Henry Royce's Secretary}210 Outer } 57 " 83.9 " Total 82 " 142.1 " R.S. 209 Inner } 20.75 lbs. 41.5 lbs. R.S. 211 Outer } 60.0 " 133.5 " 80.75 " 175.0 " The existing springs on the O.H.C. unit surge very badly over almost the complete speed range. Running with the outer springs only (inner removed) both the inlet and exhaust valves bounce at 4,000 R.P.M. It is seen that the seat loading of the valves, even with the inner springs removed, is higher than standard. We suggest therefore that the lift of these cams is unnecessarily high, and that we would stand to gain a lot from reduced lift and lower max. accelerations. The Design Dept. can be supplied with the static weights of any parts of the valve gear. As previously reported, the tappet noise is considerably amplified by the method of holding down the rocker cover. This should be modified. Exhaust Valve Expansion. In a previous report we have stated that the maximum expansion of the sodium cooled exhaust valves was no more than .001". This test has been repeated, and this time we have made certain that the valves did reach their maximum expansion by running at weakest maintained petrol consumption. Method of Test. A micrometer measured the valve expansion by making an electrical contact with the top valve spring washer. This mike is clamped to the camshaft housing. | ||