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).
Experiments and modifications conducted on a Phantom II petrol pump, comparing its performance with an A.C. pump.
| Identifier | Morton\M19\ img254 | |
| Date | 3rd October 1931 | |
| To E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/W.Bell. Hs{Lord Ernest Hives - Chair}/Bell.1/ADL 3.10.31. LeC.2907/9. P.II PETROL PUMP. x7460. The following experiments were taken with a standard petrol tank and petrol pipes in the suction circuit, with a cam lift of .250". The P.II pump supplied did not equal the delivery curve I of the A.C. pump under the same conditions. The most noticeable difference observed during the tests was that whilst the A.C. lever followed the cam practically throughout the range, the P.II pump left the cam slightly at the higher speeds when using a back pressure of 1 lb/sq.in. and without any back pressure left the cam throughout the range, at some speeds losing (at a modest estimate) 25% of its stroke. Several different springs were tried and ultimately found that an upper spring giving 8 1/2 lb initial load in conjunction with a lower spring of 20 lb initial load gave the best results of the combinations tested. By fitting the A.C. head to the P.II pump and using the 8 1/2 and 20 lb spring, the results were improved considerably although even then the tappet tended to leave the cam. The inlet and outlet passages and valve ports of the P.II head were then opebed out to the same dimensions as those in the A.C. head. The valve stops were converted to pin stops as in the A.C., also a set of A.C. diaphragm fabrics were fitted. These modifications, although effecting a slight improvement (curve 2), failed to reach the desired results. By fitting an anote filter (minus the filtering elements) directly to the inlet of the P.II head, a definite increase in delivery was obtained giving slightly better results than the P.II with the A.C. head, Curve 3. Re. the fabrics. The centres of the holes in the P.II fabrics are just equal to those of the casings (i.e. 2.700"). In the A.C. the fabric centres measured .050" more than those of the casings, thus allowing a slight amount of flexibility (viz. fabrics 2.800" CTS.{C. Trot Salt - Carburation} casings 2.750" CTS{C. Trot Salt - Carburation}) It was noticed after stripping and rebuilding the P.II pump several times, that the faces of the casings were not flat due to the weakness of the metal round the screw holes. Hs{Lord Ernest Hives - Chair}/W.Bell. | ||