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).
Fuel distribution tests on vertical carburettors and induction systems.
| Identifier | ExFiles\Box 179\2\ img040 | |
| Date | 10th December 1931 | |
| R.{Sir Henry Royce} From Ha/Ma. C. to BG. MrT. C. to S. Da.{Bernard Day - Chassis Design} C. to Ey. ORIGINAL X1487 Y5080 DISTRIBUTION. VERTICAL CARB. J.I. In curve No.51, we shewed that, except at full throttle speeds below 1000 RPM, the induction system illustrated in Photograph I was ideal for distribution. In view of the fact that all the new designs of R.R. carbs are of the vertical type we carried out two further tests with a vertical S.U. arranged as in Photograph II. The results are shown on curve No.52. The fan shape, in which the fuel leaves the jet on these S.U. carburetters, appears to be an asset on these T shaped pipes in getting cyls 3 & 4 rich enough, because when this fan is thrown across the induction pipe instead of along it i.e. the air valve parallel to instead of at right angles to the crankshaft, the distribution is spoilt at the lower speeds. Actually with the carburetter as in the photograph II the distribution can be considered very good correcting the fault on the horizontal carb. On the other hand we know from our results on the 40/50 that the horizontal carb. can be made to give almost perfect distribution. We are now carrying out a test varying the length of the uptake to see if it affects the distribution or the power. Our only impression from previous tests about this is that if we increase the induction pipe capacity too much we may spoil the crisp response to sudden accelerator depression. It is encouraging that we have found it possible to get good distribution with a single jet carburetter either vertical or horizontal, as long as we do not have any bends. Ha/Ra. Print attached. | ||