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 performance tests using various fuels, including paraffin mixtures, on Goshawk and 40/50 HP models.
Identifier | ExFiles\Box 31\4\ Scan033 | |
Date | 26th July 1922 guessed | |
contd:- -2- We have carried out tests which show that a carburetter will work perfectly on Aviation petrol or Benzol but if inferior petrol with paraffin added is used, there will be a definite hesitation or popping when picking up. With the poor petrol, the Goshawk will run a considerable distance pulling hard at 10 m.p.h. without loading up. We have tried the S.U. carburetter using inferior petrol. We find that this gives the same characteristic as our own i.e., with Aviation petrol one can weaken right off and there will be no hesitation in picking up but with a paraffin mixture there is a definite hesitation picking up. We carried out tests on the road on a Goshawk by heating up the portion of the carburetter round about the butterfly throttle valve by means of a blow lamp. We found that this made a definite improvement. We have also tried supplying hot air to the carburetter. This we find makes a slight improvement. On the 40/50 HP. car we find that there is the same tendency of hesitation when picking up if we use paraffin mixture. With the exhaust heated throttle it is considerably improved. Acting on your instructions that we should measure the vacuum actually in the carburetter when these faults occur with the car running on the road. We obtained two air valves which had the same characteristics. We could change them about and get exactly the same results. One of these was fitted in the carburetter in the usual way and the other was fixed on to the instrument board on the car. The chamber at the top of each air valve were then connected together contd:- | ||