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).
The investigation into the burning of exhaust valves on the 20-HP chassis.
| Identifier | ExFiles\Box 48\4\ Scan121 | |
| Date | 18th January 1924 | |
| Hs.{Lord Ernest Hives - Chair} X4226 EP{G. Eric Platford - Chief Quality Engineer}14/H18.1.24. 20-HP Chassis. Burning of Exhaust Valves. As requested, we have tried to produce the burning of the valves on the unit test bed, but we have only been able to do this by running the engine continually at high speed, full power, with the exhaust pipes removed and ignition plugs being used which we know cause preignition. We cannot conceive that this condition can prevail on the road, and think there must be some other reason. It was noted when making this test, that in the case of the faulty valve which Mr. Warwick has taken, after running only a short time in a pre-ignition state the valve seating had gone and compression was lost. When examining the valve it was not found then to be burnt as those we have already experienced, and even now only shows slight signs of burning after considerable further running in this condition. The other valves running under the same conditions remain satisfactory, and as regards seating and compression continue to be good. It was also noticed that with these valves the tappet clearance did not alter, but that No. 5. exhaust valve, i.e. the one which failed the clearance was continually being taken up. In checking the condition of the seating of No. 5. valve, it was found that the seating and the valve face were not true, and evidently this distortion had taken place early on. We do feel that when valves once start leaking the burning of the valves is aggravated. We suggest therefore our investigations should be as to the cause of the seating distortion, and in order to get somehwere on this job, we suggest that on any Experimental car which is being run, and on the 10,000 mile production car now being tested, an inspection report should be made out after each long run, so as to note the variation, if any, and whether there is anything consistent in this variation and the burning out of the valves.. It was noticed that the distortion of the valve seating itself was only very slight indeed, and [Handwritten note in margin]: of the tappet clearance & compression | ||