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).
Engine power loss issues and various mechanical failures.
| Identifier | ExFiles\Box 133\3\ scan0067 | |
| Date | 6th March 1939 | |
| -7- Power Loss. A power loss of some 14 BMEP was experienced on the cylinder and was ultimately traced to (a) Loss of turbulence due to improved breathing with smoother inflow of air to cylinder. Replacing original valves pulled the power up by 10 MEP. (b) Incorrect exhaust camshaft - accounted for 2 MEP. (c) increased motoring losses which were 4.5 lbs/sq.in. greater. (d) Overheating of the injector, which had been fitted with an extra sleeve between the injector body and cooled housingto take up an excessive clearance introduced by faulty machining. Compression Pressures and Volumetric Efficiency. Increased over the speed range from 510 lbs/sq.in. to about 530 lbs/sq.in. Volumetric efficiency was about equal to that obtained on the original cylinder. Mechanical Failures. Pistons. Two failures were experienced, viz:- a cracked skirt due to excessive skirt clearance, and cracks developing from an oil hole in the gudgeon pin boss. Bearings. One W/M bearing wore out, exposing the steel shell after 150 hours. Camshaft Drive. Vertical drive bearings had siezed. Injection Pump Elements. Four failures, two due to cracking, and two due to siezing probably resultant on some dirt getting into the valve. Valve Springs. With high lift cams, bounce set in over 2000 R.P.M. | ||