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 run report for an S.U. carburettor, type H.V.5, on a 12-GIV chassis.
| Identifier | ExFiles\Box 31\4\ Scan063 | |
| Date | 4th August 1931 | |
| For files. TEST RUN ON S.U. CARB. 12-GIV. This carb. having 1 5/8 throttle dia. type H.V.5. fitted with needle W.O.3. was run a total distance of 732 miles on 12-GIV. The run included Porlock, Lynton and various other Devonshire hills. The car suffered from intermittent clutch slip and for 300 miles was run on magneto owing to failure of the battery ignition. This appeared to affect the consumption adversely. The total petrol consumed was 50.25 galls. for 732 miles or 14.9 M.P.G. For the last 300 miles on battery ignition the consumption was 15.7 M.P.G. average speed 35 - 40 M.P.H. 18-GIV on the last 10,000 mile test was only averaging 15.6 M.P.G. at 38 M.P.H. However, this is not the best we can do for economy and it is worth doing consumption tests with various needles. The car was run on Shell Mex, Shell No.1, Pratts Commercial and R.O.P., functioning well on all spirits. General snap opening up better than the standard R.R. carb. Slow running very fair as long as the mixture control is kept in the full weak position, otherwise hopelessly over-rich and engine hunts. Most objectionable feature - hiss at partial throttle openings, most noticeable at 40 M.P.H. cruising. No flat spots. On the whole this carb. functions remarkably well and would normally be worth developing with (1) Auxiliary slow running device. (2) Silencing. (3) Good petrol consumption needle. It shows that an engine need not necessarily have a "woolley" feel when fitted with an expanding carburetter. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||