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).
The performance and modifications of a carburetter, autovac, inlet pipes, and ignition plugs.
| Identifier | ExFiles\Box 11\3\ 03-page231 | |
| Date | 20th July 1930 guessed | |
| -9- on the thread causes it to jam. The carburetter generally has functioned correctly after slight attention to the air ports. With the use of the commercial spirit, we found that an approx. setting of 3 notches stronger was necessary to obtain the best acceleration and correct mixture under all conditions. The modified petrol inlet has given us ample petrol for consistent high speed work. There is the same feature with this carburetter as was experienced on 23-EX, i.e. oil draining out of the pipe after the engine comes to rest. This feature appears to be due to the suction of the carburetter, as we have tried running with the air breather pipe taken off the engine, and practically no oil was flung out with the revs. of the engine. We have had no trouble whatsoever with the air valve sticking or working loose. AUTOVAC & PIPING TO L.O.P. F.80789 - LeC.2801 Revised to suit new position of Petrol Filter on Dashboard to LeC 2801. There has been no trouble with the Autovac. The supply of petrol has been maintained right down to the last 1/2 gallon in the rear tank. We have since fitted a new autovac sent out from Derby to give an increased supply of petrol for continuous high speed work, but previous to fitting this we had not experienced any shortage of petrol. The position of the filter on the dashboard is quite accessible. We have on several occasions had to clean the filter whilst on the road. INLET PIPES TO L.O.P. E.80311 - LeC.2798. (1) Exhaust Heated Bend. (2) E.80899 Cover replaces E.80285.- The inlet pipe has not shown any sign of fractures or weakness, there has been no trouble whatsoever with it. With the use of the commercial spirit, there is insufficient heat to the exhaust heated bend. We found during the test that a weak mixture is prevalent until the water temperature has reached a minimum of 75°C. After starting up in the morning, although the mixture was put over strong, good acceleration or power was not obtained until the above temperature of water was reached. It has also been very susceptible to the varying temperatures whilst on the road, this being chiefly due to the radiator shutters not closing with the cooling down of the engine. IGNITION PLUGS.- We have run with 6 MC.3 - 50 Lodge plugs fitted to the coil ignition and one in the magne to, and 5 standard C type in the remaining positions. The MC.3 - 50 type do not show the same tendency of the electrodes burning as the standard C type. We have not had any failure of either plugs. Pre-ignition has been noticeable after a hard run, but not to any serious extent. | ||