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 the limitations of the vacuum petrol supply system on a 40/50 chassis.
| Identifier | ExFiles\Box 40\4\ Scan018 | |
| Date | 22th November 1920 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to Cj. c. to Bn.{W.O. Bentley / Mr Barrington} c. to E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to By.{R.W. Bailey - Chief Engineer} c. to EP.{G. Eric Platford - Chief Quality Engineer} c. to EWT. for R.R. Inc. X3579 Hs{Lord Ernest Hives - Chair}6/LG22.11.20. X3579. VACUUM SUPPLY FOR PETROL SYSTEM. X.3503. We have carried out the following tests in order to show the limitations of the vacuum system of petrol supply. On a standard 40/50 chassis the height from the bottom of the petrol tank to the carburetter jets is 12" to 13" when the car is level. We require at least a head of 9" above the jets in order to maintain the right level of the float chamber. This means that with the car level the vacuum must lift the petrol 22". If the car is climbing a gradient of 1 in 4 the petrol must be lifted 50". We have tested the vacuum in the induction pipe on a 40/50 car on the dynamometer. We measured the vacuum in inches of mercury and inches of petrol. The following are the results:- REVS. full throttle. Lift ins. of petrol. Lift ins. of mercury. 300 12" .625" 400 14.25" .687" 500 16.25" .812" 600 18.75" .937" 700 22.0" 1.125" 800 24.0" 1.150" 900 27.0" 1.400" 1000 30.5" 1.562" Vacuum measured at primer cock. | ||