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).
Engine modifications and ongoing issues with the exhaust manifold, timing gears, pistons, and oil system.
| Identifier | WestWitteringFiles\S\September1928-October1928\ Scan173 | |
| Date | 18th October 1928 guessed | |
| Contd. -2- The exhaust of this engine is rather noisy; the noise apparently penetrates the comparatively thin material from which the manifold is made. The brazing of the large flange on the manifold failed due to the heat after a few minutes full power running. This has been overcome by welding. The manifold has become very distorted, due no doubt to the thin material. A caste-iron manifold would probably be quieter. The timing gears have now been quietened. There is no marked improvement over a standard set of gears, which could be attributed to the new method of construction. The pistons have been eased on the hard marks and lapped in the bores, and they now run considerably quieter. As the engine has not done very much hard running since, the pistons are being carefully watched for any noise developing. The size of the ball-valve seats of the oil relief valve have been increased from .384" to .462" dia. with a view to preventing oil flooding the rockers and escaping behind the fan pulley at high speeds. Although this alteration has reduced the rocker oil pressure by 33% at 2500 r.p., the flooding still continues. As pointed out in a previous report the oil pressure to the auxiliaries varies considerably with the speed of the engine, due to the large quantity of oil with which the relief valve has to deal. The capacity of the pump is approx. 7½% larger than the standard Phantom pump; and, as over 50% of the oil delivered is rejected by the relief valve, | ||