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 results on petrol gumming, its effect on needle sticking, and recommendations for prevention and cleaning.
| Identifier | ExFiles\Box 103\5\ scan0170 | |
| Date | 1st February 1939 guessed | |
| - 2 - encouraged to quicken the test. The fresh petrols did not produce any stuck needle, nor did one with "Adcoid" added, but with two "aged" petrols, in which gum formation had thus been induced notice the results:- Petrol A Petrol B Petrol A plus "Adcoids". No. of tests 32 32 16 No. stuck.. 28 27 9 Per cent. Stuck.. 88 85 56 It was noticed that moist atmosphere contributes to needle sticking. What to do The best way to avoid troubles due to gumming is to prevent gumming. If cars have to be kept in store for a time, see that all petrol is emptied out of the tank and that the fuel system is dry. If, however, a tank already has picked up deposits on its inside surfaces, and if gum is suspected in the pipes, pump, etc. the only substance to touch such deposits is acetone. Needles, valves, etc. can be cleared of gum with acetone in about 20 minutes, but a tank may need treatment for 24 hours to shift the deposits. Acetone is highly inflammable and needs careful handling, that is the only snag. If fresh petrols are always used, there should not be any gumming, but old discoloured petrol is prone to this trouble. | ||