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 review of the carburetter performance on an 8-Cylinder Buick.
| Identifier | ExFiles\Box 122\4\ scan0068 | |
| Date | 15th January 1935 | |
| To E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Bwdl. c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Bwdl.5/KW.15.1.35. 8-Cylinder Buick. The general performance of the carburetter on this car is good, noticeably in the ability to get away when cold. It is a twin down-draught of the fixed throat type and fitted with an accelerator pump, being produced by the Marvel Co. Information from General Motors shows that it has now been superseded by a Stromberg model, with improvement to part throttle difficulties. The curve of induction pipe depressions submitted by General Motors shows a figure of 2.4 ins/Hg. at 4,000 r.p.m., although we registered only 1.5 ins/Hg. at the same speed. In addition to the use of an accelerator pump, the good "get-away" when cold is considerably augmented by the "hot-spotting" arrangement which is shown on Lec.4226. A flap valve controlled by a Bi-metal strip is closed when cold, and upon starting from cold forces all the exhaust through the hot-spot. As the exhaust warms up, the bi-metal strip allows the flap valve to open, which short circuits the hot spot, this now only being heated by contact with the exhaust manifold. Another special feature is automatic strangling for starting when cold, controlled by the induction pipe depression in conjunction with a bi-metal strip. Referring back to the "hot-spot", if the throttle is snapped open when cold the exhaust pressure is sufficient to overcome the effect of the bi-metal strip and open the flap valve. As tested, with the existing setting, the mixture appeared to be on the rich side, especially when slow running at 5 m.p.h., causing the running to be bumpy. This did not produce any transmission chunking, but we are inclined to think that such running on an R.R. chassis would be sufficient to cause chunking, thereby condemning the slow running as being poor. | ||