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).
Technical report on vehicle performance, detailing issues with the engine, valve rockers, and carburettors.
| Identifier | ExFiles\Box 125\2\ scan0180 | |
| Date | 10th December 1934 guessed | |
| - 2 - SECOND GEAR EQUIVALENT TO OUR THIRD. Speedometer. Seconds. 10 to 20 4 1/5 10 " 40 8 2/5 10 " 60 16 1/5 The useful acceleration figure in this gear is up to approximately 57 MPH. The car held the track very well and did not show any distress upon completion. The enamel on the exhaust pipes had, however, practically been burnt off near the outlets, and one exhaust joint of a manifold was blowing. ENGINE. The power has been smooth and very good up to 80 MPH. speedometer; above this there was a distinct roughness. It has been free from misfires and no sign of preignition. It becomes very dirty by the water and sludge being thrown up; grit and small stones being found on the tray between the cylinders. The engine guards are inadequate. There was a slight exhaust period between 40 and 50 MPH. It has been very free from oil leaks. Oil consumption has not increased, keeping an average of 1190 MPG. The valve rockers were quiet up to a mileage of 4691 (the car had previously run 6063 miles). At this mileage one rocker was noisy starting up and running light. At 4870 miles several rockers on the NS.{Norman Scott} bank of cylinders were noisy running light, and at 5000 miles they were persistently noisy, also intermittent on the OS. bank of cylinders. The NS.{Norman Scott} rockers were dismantled. They were covered with carbon sludge and the oil feed holes in the rocker shaft were partially choked. The chief trouble, however, appeared to be the mushroom valves not seating in the hydraulic plungers. They were quiet after thoroughly cleaning and re-assembling. The OS. was left for further developments. There is an Autoclean type of filter in series with the oil supply to the rocker shafts, but it does not appear to be adequate. The only other kind of filter is a perforated tray situated in the sump, but which is of no value for cleaning the oil. CARBURETTORS. The thermostatic operation of the carburettor chokes has not given any trouble, and has been quite effective in operation during the warming up period. There has been no difficulty in starting up or getting away from cold. The carburettors failed completely due to faulty design. The carburettor float chamber covers are a thin stamping and rely upon a paper washer to make the joint. There is nothing solid, and the paper joint shrivelled up allowing water and sludge thrown up to enter. This caused the automatic choke flaps to stick on one occasion, and stoppage of petrol on two other occasions. | ||