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 faults and corrective work carried out for chassis B.260.GA.
| Identifier | ExFiles\Box 131\4\ scan0300 | |
| Date | 15th June 1937 | |
| To W/P from Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} continued. Re: Chassis B.260.GA 2. 15.6.37 No. 4 Con.rod could be rotated half an inch before the bearing moved, owing to slackness in the bearings in the Con.rod housing. The remaining rods could be rocked over sideways, showing a barrel shaped bearing. They were in a poor condition for fit when examined, and would allow excessive oil to escape. A width of approx. 5/8" was all that was bearing on the pin journals and this portion was too tight. Upon trying to turn the crankshaft with rods removed, it took some effort to move it; afterwards it revolved freely. No. 4 main bearing was found to be the cause. It was too tight and was not fully tightened up. When fully tightened up the crankshaft could not be moved. The stepping of the shims had not been a good job. They were not let down evenly and were tight at one end and slack at the other. The result was the bearings were bedding hard on one side and not the other. Investigation found both the front and rear acme threads were fouling, causing oil leaks. It was necessary to remove the engine from the frame to correct these faults and re-bed all the bearings. The cylinder block bores were not in a bad condition, No.1 being the worst with .004 ovality. The following work was carried out: (1) New Cylinder Block with ground bores standard size fitted. new pistons and hammered stressed rings fitted. (2) Crankshaft bearings rebedded, and new stepped shims fitted. (3) New bearings fitted to Con.rods and given .002 nip. (4) Front case fan drive aperture scraped out to give clearance for acme thread. (5) Rear of crankcase scraped to give clearance for acme thread (6) Piston rings and cylinder bores lapped slightly to give initial bedding. (7) Cylinder head thoroughly cleaned (There had been water leaks from the gasket). (8) All valves reground and new grummets fitted. (9) 25/30 Crankcase breather fitted, and rocker cover breather blanked off. (10) Air cleaner washed out. | ||