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).
Chassis 93 NK after 2,915 miles detailing engine performance, oil consumption and exhaust issues.
| Identifier | ExFiles\Box 71\4\ scan0126 | |
| Date | 11th April 1925 | |
| X8940 Hotel de France, CHATEAUROUX. Indre. GWH.{George W. Hancock - Head Chateauroux}I/Crn.II.4.25. To: "HS{Lord Ernest Hives - Chair}" From: G.W.Hancock. Report on chassis 93 NK after 2,915 miles. (Handwritten above: 3,000) ENGINE. General performance very even and good. Magneto drive O.K. - (LEC's 2019 & 2028). Oil relay working satisfactorily. Slight weep of oil from oil relay drive. Controls O.K. Pistons over-oiled - carbon deposit fairly heavy. Plugs - fair amount of carbon deposit. All plugs still O.K. Wiring O.K. Make & break points battery ignition badly pitted & dirty - these have been filed, cleaned and reset. Slight leak of oil from water pump drive rear of gearcase. Water pump housing O.K. Water pump packing O.K. Tappets - Nos. 5 & 6 reset to .004" cold, from .003". Tappets required very little attention. No.I tappet clicking at bottom of push-rod. Oil consumption excessive. We have proved that at high speeds oil is getting passed pistons and being burnt away, also oil to rocker shaft is excessive, oil consumption is worse. We believe that it would be an advantage if oil temperature could be kept down. On yesterday morning's run, the temperature of the oil reached 80°C. The average temp. of oil works out at 70°C. We suggest ribs on bottom half of crankcase, to cool the oil. Engine suspension on front quite O.K. Exhaust boxes - The rear exhaust box has broken the dowel flange off (centre of engine end). We have noted that the expansion actually of these boxes is in the opposite direction to that provided by the D.O. We believe it is due to the following : The exhaust box becomes the hottest at the down-take ends. Consequently, the expansion here will be greatest. This combined with the pipe, tending to hold the box more rigid, tries to expand towards the centre of the engine. This is proved by the relative position of the dowel pins, as they are now. The following sketch will shew this :- [Sketch of an exhaust manifold with handwritten annotations: 'when from new', 'lugs', 'when broken', 'exhaust'] The expansion of the cylinders may be in an upward motion, which is the cause of the flange becoming cracked. Cast-iron choke valve in down-take pipe - this has stuck open recently during high speed run. Dismantling shews spindle slightly distorted, but this valve still rattles when engine is running normally. Exhaust pipes do not shew any tendency to scale. Fan and drive O.K. Engine louvres - after very dirty & wet run, slight amount of dirt had got up on to dashboard on exhaust side. Relief valve unit (oil) - this should have better protection from dirt. If oil pressure drops, and it is necessary to take this oil unit down, it is almost impossible to prevent dirt getting into the valves or on crankcase face, which means when refitted oil leaks. Also, it is in a very inaccessible position. We have been running | ||