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).
Two proposed schemes to fix sticking air valves on the 20/25 HP car.
| Identifier | ExFiles\Box 102\1\ scan0153 | |
| Date | 15th February 1934 | |
| re Sticking Air Valves - 20/25 HP. Car. There are two schemes at present in hand to overcome this defect. The first scheme deletes the snift holes and the air which on the present design passes through these holes direct from the atmosphere is taken in through the air silencer and filter and it is expected therefore that dirt and dust will be trapped before reaching the air valve. This scheme is only applicable to carburetters with the resonance air silencer (Chassis No.GLZ.1 onwards) and necessitates a machining operation on the carburetter suction chamber. In the second scheme (of Experimental Dept.origin) the snift holes are retained, an annular clearance of .005" is allowed between the large diameter of the piston and the dashpot, and a stainless steel ring is pressed on to the lower end of the piston and replaces the present guide at this point. This scheme is applicable to all existing carburetters and to apply it in the case of a persistent complaint it should only be necessary to supply a new piston. We understand that both schemes have been tested out as regards their effect upon the carburation and have been found satisfactory in this respect. In addition, the second scheme has been fitted to and is running on 20-G-IV (C's car) which however is a resonance air silencer type of carburetter. A second set of parts is being made and will be tested out on a customers car fitted with the old type of carburetter. At the moment the second scheme appears the most hopeful because it applies to all existing 20/25 HP. cars and does not require extensive modifications to apply it in cases of complaint. With the introduction of the RR. S.U. type of carburetter, hoped for on the series following D.2. this trouble will disappear. | ||