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).
List of required modifications and points to be included in a new drawing for a carburettor system.
| Identifier | ExFiles\Box 122\3\ scan0093 | |
| Date | 4th October 1938 | |
| -2- A drawing is urgently needed either showing or mentioning the following points:- (1) Deleting the drip tray. This tray is unnecessary on Wraith because (a) The exhaust manifold is now on the opposite side of the engine. (b) In the case of a full bore flood (which in itself is very rare indeed) there are only four drips per min. for the tray to catch. (2) Stronger choke valve. The actual thickness of the new valve is 2 m/m.{Mr Moon / Mr Moore} Complete details can be supplied by Rm{William Robotham - Chief Engineer}/GR.{George Ratcliffe} Main points of the mod: larger dia. spindle with the new spring to suit. Counterbored spindle bearings (ECD.648 out of date). (3) E.60626 Ball end (throttle lever). (4) Idle system as Rm.{William Robotham - Chief Engineer}467. (5) Leather accelerator piston (strengthened type). (6) Main feed hole (Flt.chm.) = .156 dia. (7) Float chamber lid{A. J. Lidsey} E.61448 mod. but the lamp post breather should be simplified, to be similar to that fitted to the Humber 'Snipe' (see Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}) On the 'Snipe' the lamp post breather is an integral part of the floatchamber lid.{A. J. Lidsey} We cannot go quite as far as that, because we have a drain to incorporate. Further, we should not do away with the drain, which is similar, and fitted for the same purpose as that on Bentley III. The use of these drains from the top of the float chamber is solely to take care of a full bore flood (complete failure of float mechanism). Although this occurence is extremely rare, it is very dangerous if and when it does happen. The policy of fitting such drains originated when a customer had a serious fire with a 3½-litre Bentley (petrol sprayed on to spark plugs). Incidentally, the Humber 'Snipe' does not require such a drain because of the use of a mechanical petrol pump. | ||