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).
12,000-mile test report on vehicle 41 G IV detailing issues with the engine, exhaust, pistons, and connecting rods.
| Identifier | ExFiles\Box 5a\4\ 04-page100 | |
| Date | 28th August 1934 | |
| X5840 Hotel de France, Chateauroux. Indre. France. To SQ. From G.V.H. c. W.R. c. ST.{Capt. P. R. Strong} HS.{Lord Ernest Hives - Chair} c. BT.{Capt. J. S. Burt - Engineer} MS. 28th August 1934. REPORT ON 41 G IV - 12,000 MILES. ENGINE. G 14 UNIT. The mounting of the engine on rubber has damped out the vibration and periods from the frame. A roughness, however, could be felt on the pedals, and vibrations were transmitted to the change speed lever. This roughness became very noticeable towards the latter mileage, the dropping of the rear mounting being the cause. This roughness disappeared, and it was actually smoother than when the mileage was first commenced, after it had been packed up to its original height and alignment. The power has been up to standard. There has been, during the latter mileage, an uneveness of running due to weak carburation. This has been caused by the stretching of the studs holding the manifold and induction pipe to the cylinder head; producing an air leak. The hydraulic adjustable tappets also have held the valves open, causing uneven running, both at low and high speeds. The maximum speed of the car taken on the Monthlery track was 71.98 miles per hour with the hydraulic rockers in action, and with a standard set of rockers, 74.37 miles per hour. EXHAUST MANIFOLD. The exhaust manifold has broken at approximately three inches from the flange of the 3 and 6 exhaust port. The manifold had contracted to its limit allowed, before it broke. It first cracked while cooling down standing in the garage with a sharp report. FRONT EXPANSION BOX. The front expansion box made in a standard steel, lagged, did not show any scaling after 8,000 miles. The staybrite lagged expansion box has shown no deterioration after 6,000 miles. PISTONS. There has been a double piston knock throughout the mileage. These pistons have the double slot horizontal. We examined the pistons and found the bedding was chiefly on the gudgeon pin sides, and very little on the pressure side. The skirts have collapsed. The knock was due to too slack a piston. Carbon deposit was normal on the piston heads. CONNECTING RODS DRILLED UP THE CENTRE. Nos. 1, 2, 3, 4 and 5 top half of the connecting rod bearing the metal had cracked and pieces approximately .375 in circle had become detached when examined. The bottom bearings were intact. | ||