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).
Test report on fuel pump failures due to temperature, comparing standard and high lift pumps.
| Identifier | ExFiles\Box 149\4\ scan0016 | |
| Date | 2nd October 1936 | |
| -3- In this case the high lift pump was fitted in the dash position and the whole of the increased head was available at the carburetter and with the standard carburetter it would not be possible to use a much higher pressure without risk of flooding. In conclusion, a pump with a greater delivery pressure would improve the situation up to a certain temperature limit, after which complete failure would occur, namely, between 55°C. and 60°C. Complete Failure of the Pump due to Temperature. During the previous tests it became evident that the temperature of the petrol reaching the pump was the chief factor causing failure. A series of tests were carried out with fixed under-bonnet temperature of 60° & 70°C., with the petrol at different temperatures (See Graphs Nos. 2, 3 & 4). The Standard Pump. The delivery fell off as the petrol temperature increased, and failed completely between 55 and 60°C., the shortened stroke pump being more erratic. With the stiffer G.3 material diaphragm the delivery was down to start with, but was slightly better maintained at the higher temperatures though it also failed between 55° and 60°C. The High Lift Pump EX.1. The delivery of this pump was well maintained up to 55°-60°C., when complete failure occurred very suddenly. It was observed in all these tests that the level in the float chamber dropped 5/16" while the flows were being taken, and a test was made to find the head of petrol required to pass 112 pints/hour through the float needle valve, this was found to be only 6 1/2". | ||