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).
Engine performance testing, focusing on carburettor development, induction, and valve bounce.
| Identifier | WestWitteringFiles\S\June1928-August1928\ Scan140 | |
| Date | 28th August 1928 guessed | |
| contd :- -2- like to raise the peak to 3000 r.p.m. which may be possible by different valve timing or different angular relationship of the cams. The induction pipe depressions are low - 2.4 ins. at 2750 r.p.m. - and we hope to be able to work somewhere near these values when we get the new RR. expanding carburetter, which should possess considerable advantages over static carburetters in maintaining good suction on the petrol jet at low speeds. We shall try various size XX chokes in the present Claudel carb. so as to determine the minimum area and required depression to give us our maximum power output which will give us a basis to work upon with the new RR. carburetter. All the tests have been made so far with a cold induction pipe and the distribution appears reasonably good, but as we have previously found with Claudel carbs., is influenced by the position of the air intake. There appears a tendancy for the end cyls. to be rich. We shall investigate the induction pipe question later but from these preliminary tests it appears that the six inlet ports give us better distribution than our previous system of four ports. With regard to the power falling off at 3000 r.p.m. we think this may be due to valve bounce and will investigate this point. As previously reported we had trouble with the plain bush in the dynamo drive seizing up. We are now having a spiral oil groove put in the bush. The above tests have all been carried out with one ignition only because we have not yet fitted the new bush. contd :- | ||