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).
Detailed report on engine troubles experienced during a 15,000-mile test of the Phantom III.
| Identifier | ExFiles\Box 91\1\ scan0282 | |
| Date | 20th May 1936 | |
| 35-1 To E.{Mr Elliott - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} c. to MX.{John H Maddocks - Chief Proving Officer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}11/KW.20.5.36. 15,000 miles Test - Phantom III. We gave a brief summary of the troubles experienced on the first 2,500 miles of this run in the daily report. We give below a more detailed description of these points. ENGINE. With regard to the vapour lock, two types of carburetter venting were tried, one the float chamber drain scheme now on production and the other the vent scheme to the intake silencer. We do not think either of these schemes is as good as the one at present fitted to the 20/25, and from our conversation we understand you are in agreement that we should use this arrangement on the Ph.III. The new part can easily be fitted to the cars at the Coachbuilders. The vent to the air silencer was better for vapour lock than the other scheme, but definitely affected the mixture strength which we think is a disadvantage, as depression in the intake silencer is bound to vary with the condition of the air cleaner. We tried both schemes of filter position; i.e., the one on the rear cross member and the one by the change speed mechanism, and in neither case did we suffer from starvation of fuel feed. The weather was not of course exceptionally hot but an under bonnet temperature of 80°C. was reached, which at least indicates that the car would be free from trouble in anything but exceptional conditions. We think it is inevitable that Ph.III's will top overoil after a certain mileage with the present valve arrangement. On our car, in addition to the production scheme we had the outside drain on the cylinder head and yet oil had begun to come down the valve guides at 2,500 miles. We think it is unreasonable to expect the grummets to maintain 100% sealing condition. The only solution appears to be some sort of shield on the valve spring, and we are carrying out experiments with this. Fortunately the top overoiling does not seem to have any very serious consequences apart from a smoky exhaust, judging from the | ||