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).
Carburation for car 7 CA, comparing the C.H. carburetter with other types and discussing induction pipes.
| Identifier | Morton\M11\ img038 | |
| Date | 6th June 1917 | |
| ORIGINAL. To EH. from R.{Sir Henry Royce} C. to J.{Mr Johnson W.M.} R6/B8:6:17. [STAMP: JUN 1917] 4 X:682 Re Car 7 CA. Regarding the carburation on 7 CA, it should be quite understood that the C.H. carburetter may be very useful for demonstrating what power you can obtain from the car engine, but I cannot imagine how it can possibly be any use expecting to get perfect road running from any other type of carburetter except one which is fully automatic and expanding in size with the opening of the throttle. At the moment we know of no carburetter to fit the engine other than the type fitted to the White Knave or the London to Edinburgh type, which I believe has the medium size throttle, a fairly small low speed throat, and a large high speed throat. It was estimated that the White Knave had twice the area when compared with our original standard two jet, and therefore ought to give quite a good horse power with the improved valve lift. It is also the only throttle which would work freely enough to be controlled by the governor. X.2939 B Regarding the induction pipe, I do not know what pattern of pipe will give the greatest horse power with good distribution, but it would be of little use fitting anything but what could be applied to this "immediately after the War" chassis. It will be remembered that I shall require the car to be in Peterborough by Saturday morning, the 16th. inst. [Handwritten note in right margin]: For R Instruction should be in course of issue X.2937 B. permanent high lift cams further improvement [Handwritten note at bottom]: HP/R.{Sir Henry Royce} Since writing the above I have seen your memo showing over 100 BHP with L.G. carburetters & standard induction pipe which seems v satisfactory, shall await with interest any [Faint text at bottom left]: R R 538V (400 L) (2 C PSC 19-3-16) L122V | ||