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).
Carburettor jet issues causing blow-back at certain speeds and potential solutions.
| Identifier | ExFiles\Box 130\2\ scan0128 | |
| Date | 1st September 1936 | |
| X1113 Will you please let me know if you have any objection to this jet. Rm.{William Robotham - Chief Engineer} To Hs{Lord Ernest Hives - Chair}/C.T.Salt. Cricklewood, Sept. 1st, 1936. With reference to your memo. Hs{Lord Ernest Hives - Chair}/CTS.{C. Trot Salt - Carburation}26/KW.31.8.36. The sentence should have read, by increasing the metering jet to .0635" or 1.6 m/m.{Mr Moon / Mr Moore} The present jet is stamped 063 (actual dia. 1.5 m/m). The trouble being experienced on many cars in service is, at half throttle (approx.) between speeds of 40 and 50, but chiefly 50 M.P.H. there is a definite weakness which in some cases causes a blow back in the carburetter, in other cases the car luffs up. Cricklewood are receiving recurrent complaints, and up to the present have been getting away with it by either fitting a set of new ignition plugs or thoroughly cleaning the old ones. It lasts for a day then the trouble is again apparent. Paris Trails car was very bad, a kick in the back was received every time when 50 M.P.H. was reached. It is not noticeable with full throttle work. We not only cured the trouble but made the acceleration more livelier. We have not taken definite consumptions but on our own car there was no material difference. Hs{Lord Ernest Hives - Chair}/G.W.Hancock. We have since been in touch with the makers of the Stromberg Carb. and we find that they can supply a No. 64 jet which passes 12 c.c. per min. more than the 63 jet. The 64 jet as what we need. | ||