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).
Technical letter discussing issues with induction pipes, carburation, and potential solutions like the 'Dorris scheme' and exhaust heated throttles.
| Identifier | ExFiles\Box 75\2\ scan0269 | |
| Date | 20th September 1921 | |
| X2758 OY. from HS.{Lord Ernest Hives - Chair} Hs{Lord Ernest Hives - Chair}/LG20.9.21. INDUCTION PIPES. I have just received your letter OY1/G27.8.21. Re. Induction Pipes. I am very pleased to hear that you are confirming the results which we have obtained with the "Dorris" scheme. I feel that you have certainly got to help yourselves out of the carburation difficulties for this Winter. We have spent a lot of time endeavouring to make the Pilot Jet to the LeC. work. So far we have not been successful. The main fault against it so far is that it is not large enough to run the engine but I quite anticipate when it has been increased in size, that it will still be unsatisfactory, and even if it does work it will be extravagant. I am hoping shortly to hear from you as regards your opinion of the little automatic Pilot Jet we sent you some time ago. We are still very pleased with it. As regards the exhaust heated throttle, the one we have made to the LeC. is not a great success. The chief point against it is the fact that the contour of the inside of the throttle has been altered which gives us bad distribution. 4 and 5 cylinders are hopelessly strong. By applying the Dorris scheme, of course, we can improve it tremendously but we cannot make it as good as the experimental set and the Dorris scheme. We do not think it is right to rely on the Dorris scheme to correct bad distribution which can be overcome by design. The chief work for the Dorris scheme is when the engine is started up cold. I expect we shall have to go through a long and painful process before we get the throttle corrected. I am still convinced that the exhaust heated throttle is an advantage even with the Dorris scheme. You may, of course, find that applying the Dorris scheme to existing cars will make a sufficient improvement to prevent complaints. We think, however, that to get the best out of the present arrangement of engine, the exhaust heated throttle should be fitted. Some of our reports we have sent through show clearly the improvement which can be obtained by an exhaust heated throttle. We have run our experimental car 1000 miles with 20% paraffin mixture using castrol oil and having at least 20 starts from dead-cold after being left out all night, and contd:- (Text stamped upside down at bottom right: R.R.238A 160T S.H.'S. 19.8.61 (D-E-1) 8008) | ||