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).
10,000-mile report on I.B.IV., detailing engine and piston performance.
| Identifier | ExFiles\Box 82\1\ scan0311 | |
| Date | 9th December 1933 | |
| Hotel de France. Chateauroux. Indre. To Hs.{Lord Ernest Hives - Chair} From G.W.H. 9/12/33. REPORT ON I.B.IV. --10.000 MILES. ENGINE UNIT N°B.4. (BUILT as B.8.) The engine has started readily from cold. There has been no loss of power. It has been smooth, quiet, and flexible. At a speed of 3750 a certain roughness appeared and continued up to maximum speeds. This period caused the clutch pedal to vibrate which produced an objectionable noise. There has been no sign of preignition and no detonations. The acceleration although not to be compared with its previous performance with a lower geared axle ratio has been consistant and responded to the throttle opening. There is a great danger of the sump plug becoming damaged by stones or by projections on the Alpine passes. It should be level with the bottom face of the sump. PISTONS TO LOP.EB.513.LEC.3675 Heat treatment 7cHrs at 160° to 180°C - Brinell 90 to 110. The pistons were examined at 5000 and 10.000 miles for signs of failure. No vestage of any cracks could be seen either in the webs or skirts. The split portion of the pistons appears to have become distorted during the latter part of the mileage, as the bedding either side of the slot was not showing a full aera. The inner portion had collapsed. There was during the mileage for short intervals a piston knock. This has not been heard during the last 5000 miles. There has been no bedding on the lands of the pistons. All pistons rings were free in the grooves. All the small holes in the scraper rings were choked with carbon. The gudgeon pins with the pistons cold turned in the pistons and not in the rod. When warmed up they floated in the rod bearing. It would appear that a slight increase in the bearing dia. of the con. rod is needed. | ||