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).
The engine condition of chassis 93 NK after a 21,139-mile run, detailing wear and tear on components.
| Identifier | ExFiles\Box 71\4\ scan0235 | |
| Date | 8th June 1925 | |
| +8940 Hotel de France, Chateauroux. Indre. France. GWH.{George W. Hancock - Head Chateauroux}1/Crn.8.6.25. To: "HS{Lord Ernest Hives - Chair}" From: G.W.Hancock. ------------------- Report on chassis 93 NK after 21,139 miles. Engine. Engine power has been good & smooth. Compressions even. Examination of pistons shewed even lubrication, but on heavy side. This had gradually increased towards the end of the run. Heavy carbon deposit on top of pistons, and cylinder head. Valves and fittings to E.2217.B - these are O.K. The valves have been ground in three times during the 21,139 miles. Inlet valves shewed heavy carbon deposit on the top side, which means that oil has sucked down through the valve guides. The exhaust valves were free of carbon deposit. There is very little wear taken place in the valve guides, these being in very good condition. Modified cast iron choke valve in down take pipe to L.E.C. 2035 - this has stuck open once since our last report. We still think that this would be much better if the design was more robust. Carburetter butterfly throttle E.73166/7/8 - we have had no trouble with this on our last 9,000 miles. The crack in the hot spot induction pipe at the bottom corner close to flange where carburetter is bolted up, has not increased since our last report. Controls to sch. 625 - a fair amount of slack has now developed, chiefly where the compensating device is situated. There is also a fair amount of slack on control going through engine case to carburetter. On dismantling engine, to replace piston rings, we found Nos. 3,4,5 & 6 connecting rod bearings on the point of collapsing. The metal had cracked and broken up both in caps and rods. We despatched these to Derby for their examination of same. These rods had run 8,407 miles. We have been very careful during this period not to let the oil in the sump get low, also the pressure has not varied. We have run at approximately 20 lbs throughout the test. We noticed that on Nos. 1 & 2 conrods, although the metal had not broken up to the extent of the other rods, the metal was loose, i.e. leaving the steel. We assume that the continual hammering after this stage soon breaks up the metal into pieces. Drain pipes to hot-spot from induction pipe were found choked up with carbon, as also was the starting carburetter. Explosions on retard we consider to be equal to the standard 40/50 HP. car. Front engine suspension tube to L.E.C. 2027 - this is still quite O.K. Modified throttle governor spring to Sch. 632 - using spring E.5925 - this is still operating satisfactorily. Spring drive to Sch.628 - from outside examination this is quite O.K. Magneto & dynamo drive to L.E.C. 2019 & 2028 - as previously reported the fabric coupling has slightly deteriorated, otherwise the drive is in good condition. Since dismantling and cleaning the magneto, it has been rather noisy. We understand that a better designed magneto is now being made. Water pump white metal packing washer | ||