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 a 3,000-mile test, detailing engine performance and component issues.
| Identifier | ExFiles\Box 180\M3\M3.5\ img014 | |
| Date | 1st April 1925 | |
| R.R. 493a (50m) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. Expl. No. REF: GWH{George W. Hancock - Head Chateauroux}1/Cmill.4.25. C O P Y. REPORT ON CHASSIS 93-NK AFTER 3,000 MILES. ENGINE. General performance very good. Compressions are even and good. Magneto drive O.K. (Lec's 2019 and 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 and break points battery ignition badly pitted and 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 and 6 reset to .004" cold from .003". Tappets require very little attention. No.1 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 when 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. We suggest ribs on bottom half of crankcase to cool oil. The average temperature of oil works out at 70°C. Engine suspension on front quite O.K. Exhaust boxes - the rear exhaust box has broken the dowel (centre of engine end). We have noticed that the expansion actually of these boxes is in the opposite direction to that provided by 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 show this :- [Sketch of two exhaust manifold ends] Left sketch text: WHERE PIN IS NOW, LUGS Right sketch text: WHERE BROKEN, LUGS | ||