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).
Future car carburettor positioning and starting system designs.
| Identifier | WestWitteringFiles\G\June1921\ Scan45 | |
| Date | 1st June 1921 | |
| To R.H. of America Inc. from R.{Sir Henry Royce} -2- R1/G17/6/21 Contd. For future cars we anticipate it will be found preferable to abandon the present throttle and move the position of the carburettor high up, with an ample sized exhaust heated jacket lying across the top of the cylinder. We have decided that to make this jacket effective it is advisable to put a rough butterfly choke in one of the down exhaust pipes and so raise the exhaust pressure in one of the exhaust boxes when this throttle is closed. This will tend to equalise the heat of the exhaust heated jacket, making it much hotter at light loads and less hot for heavy loads. A full description of how we recommend this shall be done will be mailed next week, but the general arrangement will apply to both the present type of throttle and position of carburettor, and also to the suggested new position of carburettor with the butterfly throttle. We think the pipe to carry the exhaust heat then will only need to be about 3/8" diameter, and with a general reduction in the induction pipe we hope to get a neat arrangement. (4) STARTING. We have definitely come to the conclusion that with the carburettor in the present position it is imperative to have a small pipe leading over the top of the engine to the manifold, which small pipe will be connected to an extremely small special jet attached directly to the float feed chamber. This passage will be controlled by a cock and the little carburettor will be fitted with a choke valve. You will see that this arrangement will probably work out simpler than the combination you have got on 4 EX., as we should delete the primer, and we shall not be XXXX so liable to fill the engine or induction pipe with liquid gasoline. The drawing of this arrangement we hope to also send next week. (contd.) | ||