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).
Issue of 'running after switching off' and the role of sodium-filled versus solid exhaust valves.
| Identifier | ExFiles\Box 124\2\ scan0193 | |
| Date | 17th June 1940 | |
| Jnr.{Charles L. Jenner} from Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} c.Ev{Ivan Evernden - coachwork} 1044 Rm.{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}1/JMS.17.6.40. RUNNING AFTER SWITCHING OFF. Re: memos Rm.{William Robotham - Chief Engineer}10/ML.4.6.40. and Rm.{William Robotham - Chief Engineer}9/ML.29.5.40. In both the above memos you have stated that 11.B.V. and 30.G.VII are free from this trouble. In the later memo you have also stated that 9.B.V. and 4.B.50 are bad sufferers from the trouble. We have found on the test-bed that exhaust valve temperature is the controlling factor; the effect of water circulation will be dealt with separately. For comparative purposes, the above cars mentioned can be divided up as follows: (9.B.V. Solid a.{Mr Adams} (4.B.50 Sodium filled. (11.B.V. Sodium filled. b. (30.G.VII Solid. The only other unit fitted with Sodium filled valves is B.80 No.7 in Hs{Lord Ernest Hives - Chair}'s car (33.G.VII). All other rationalised units have solid exhaust valves. There are two points worthy of note concerning Sodium filled exhaust valves. a) In our units they are operating upside down, and it is doubtful whether the sodium is doing anything useful except at high revs. (sufficient agitation to get it into the valve head). b) Under full throttle high speed conditions, the extra stem expansion (linear) associated with sodium filled valves (as against solid valves) causes the tappet clearance to decrease. This point was covered by tests on the overhead conversion.Bentley unit, in our report reference Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}11/R.28.1.37. --- We were about to carry out a comparative test on the test bed between solid and "filled" valves, to check our past experiences with the latest set up. It would be interesting | ||