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).
Analysis of an Autovac fuel system, detailing the effect of float movement on petrol delivery and cycle times.
| Identifier | ExFiles\Box 40\4\ Scan214 | |
| Date | 2nd February 1927 guessed | |
| 4. - present capacity of the tank it would be necessary to increase the height of the tank tower by 1.20". this cannot be done owing to the Autovac fouling the bonnet, it would be necessary to lower the whole tank. Fig III gives the result of tests taken with the moving float autovac under varying conditions of free float movement; the petrol delivered varies with the float movement. The amount of petrol delivered per cycle for the different float movements is as follows:- | FLOAT MOVEMENT ON SPINDLE. | 1.2" | .9" | .6" | .3" | NIL. | |---|---|---|---|---|---| | PETROL DELIVERED PER CYCLE | 215cc | 168cc | 125cc | 85cc | 52cc. | The effect of the free movement of the float under road conditions is to increase the time taken during which the Autovac functions but also to increase very materially the period of time (between tests) when it does not work. The effect on slow running during the suction period is somewhat more marked owing to the longer time taken, but this is counteracted by the increase in time between the suction periods. e.g. If a float with 1.2" free movement were used the suction periods would occur (at) at intervals four times longer than if a float with no free movement were used, under the same engine conditions. | ||