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).
Tests and improvements to valve gear, induction systems, and timing gears.
| Identifier | ExFiles\Box 97\1\ scan0127 | |
| Date | 22th March 1938 | |
| -3- RM{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}1/MR.32.3.38. reject a number of C and A on account of a slight difference in the ferrules which were responsible for leaks. VALVE GEAR. With the flat bottom Wraith III type of tappets and the existing camshaft, the valve gear noise is a definite improvement on the B.II and almost on a par with Wraith. Valve bounce with Wraith valve springs is at 4200 RPM and further tests include trial of anti-surge springs which have variable pitch coils and designed by Ag/B. to run up to 4500 RPM before bounce occurs. These incidentally are to be used without valve grummots and this will be our first attempt to throw them away. Like the Wraith valve gear, 5/16 dia. push rods are used which overcome periods and overloading and the housing in the bottom tappet is arranged so that the push rod will never jump out of the base in the event of valve spring failure or valve sticking. INDUCTION SYSTEMS. Without any modification, the designed 4 port system with the 2 S.U. carbs. in a different position to Bentley II gave equally good distribution. From a cost point of view, however the 1 1/2" S.U. carburetters which are specially prepared for us and not a size which they produce on their line are being replaced by 1 1/2" carburetters which automatically save approx. 60/- per pair, even with improved finish (up to our standard). There is no more loss than 2 BHP at the high speeds and a more consistent distribution is obtained at low speeds. Experiments are being carried out by Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} regarding an automatic starting carburetter which if successful will delete the necessity for any mixture control. This device is already on their production line and used by several makers. The idling as tried out on the bed appears an improvement over standard Bentley but we have had so many illusions regarding what happens on the road that we would rather they give their opinion when established. TIMING GEARS. We have tested with and without cam balancer plungers | ||