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 issues such as dieseling, detonation, and potential solutions for bushings and heater valves.
| Identifier | ExFiles\Box 72\2\ scan0064 | |
| Date | 8th January 1926 | |
| -2- (2) to the appearance of the engine, but extra oil has been such a Godsend to the Silver Ghost that we believe it should be used on the Phantom. (3) We have a scheme now for a standard heater valve using your cut-out lever to operate it, but cannot say yet whether it will work. (4) We have been trying to find some sort of bushing for the choke valve spindle which would not stick or squeak. "Genelite" appears to avoid squeaking but is so soft that it distorts out of round in tightening the flange joint and makes the valve stick. With increased clearance it may be all right. Meanwhile we are ordering C.I. bushings for production. Engine firing after switching off. We ran 12-MC with thermometers stuck in every available core hole in the cylinder head, and could not find more than 5°F.{Mr Friese} variation of temperature all over the engine. So obviously that is not the trouble. We find however from the Derby model head, that it is difficult or impossible to make sure that there is not a lot of metal or core sand over the centre of the cylinder head between the inlet and exhaust bends. It may be that such a condition will make one engine form a red-hot spot in the middle of the head between the valve seats, while another has no such trouble. We know that the Silver Ghost is very sensitive to thickness etc. of the head and since we left off the little water plug in the centre of the head and the boss for the spark plug in the "intermediate" position we have had a remarkable decrease in tendency to detonate. We are now running several cars with pistons giving 4.3 to 1 compression ratio, and whereas the older cars detonate the newer one's do not. However I have not heard one of our cars continue running after switch-off, five times in five years. We have seen some spark plugs with transparent spar insulators, which enable one to see the color of the explosion. They are the "Beacon" plugs made by the Beacon Spark Plug Company, North Tonawanda, N. Y. If you want we will send you two or three sets. They should be useful in showing the rise in combustion temperature due to a hot spot in the cylinder. | ||