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).
Engine consumption tests, observed noises, and a post-mileage inspection of pistons and cylinder heads.
| Identifier | ExFiles\Box 5a\3\ 03-page170 | |
| Date | 14th December 1931 guessed | |
| -4- spirit supplied by the pumps. The average petrol consumption has been 15.32 M.P.G. Consumption tests taken are as follows :- 50 M.P.H. ... 18.25 M.P.G. 40 M.P.H. ... 21.5 M.P.G. 30 M.P.H. ... 21.5 M.P.G. A slight piston knock was heard, after 6,500 miles, in No.5 cylinder when the engine was running lightly, after completing the morning's run. It has not become definite. Engine gear rattles have been noticeable at speeds between 12 and 18 M.P.H. under load and when engine was running light. We fitted stronger driving springs in the low inertia slipper wheel at a mileage of 9,000 and could not hear any rattles during the few miles run; the car has now been handed over to FH. The master period of the crankshaft has been reached twice (momentarily) at a speed of 87 M.P.H., actual 82 M.P.H., during the mileage. PISTONS to LUP.E.55804. To give 5.7 to 1 comp. ratio. E.57122 Pistons A/2.404. E.55361/2 Piston Rings. There was a fair amount of carbon on the piston tops when we examined them at 6,500 miles. There has been no sign of gasses blowing past the piston rings. A slight knock was heard from No.5 piston during the mileage, when hot. There has been no sign of overoiling, exhaust has been clear after running lightly for 5 mins. CYLINDER HEAD & CYLINDERS to LUP.E.55824. Lec.2921 N.S.M:74. The cylinders were evenly lubricated when examined at 6,500 miles. There was no sign of any scoring having taken place. The cylinder head was taken off to locate loss of clearance in the exhaust valves that had taken place. We have previously sent a sketch and a detailed report upon what was found. The cylinder head appears to be weak around the ports. We found that through the valve guide having taken up a different angle to the perpendicular, the valves were seating lopsided, also the valve seats had shrunk in the centre. There was no sign of the seats having become burnt as was the case with 19.G.IV. but there was the distinct signs of the wear, which along with the distortion, would account for the lost clearance in the exhaust valves. There was no appreciable wear in the valve guides. There was a fair amount of carbon deposit which was not disturbed. We re-cut the valve seats, trueing them up, and have not during the remaining mileage of 3,000, lost any clearance in the exhaust valves, apparently the head | ||