Engine component condition, modifications, and performance following mileage testing.
| Identifier | ExFiles\Box 83\1\ scan0243 | |
| Date | 10th October 1936 guessed | |
| ( 4 ) Were in excellent condition. N° 5 bearing was also cracked. The other four were in very good condition. The failure has been attributed to the connecting rod chattering endways on the crank pin. The reduction inoil supply due to the play in the rear main bearings would reduce the quantity of surplus oil escaping between the big end and the crank webs, and this would allow the chattering to hammer the flanges of the bearing shells against the crank webs. A new set of Con-rods and big end bearings of the same type were fitted and were in excellent condition at the end of the mileage. PISTONS. Existing, complete set of "Aerolite" Pistons. Identification M.9 - "D" type scraper rings. CYLINDERS. LOP EB.2715. Existing, complete to above LOP incorporating:- EB.2929 Cylinder Block mod. to LeC.5117. The front 8 water holes blanked up. EB.2560 Cylinder Head - Deterbulated to LeC.5002. Cylinder bores radiused at the base of barrels to pistons scoring to RM. {William Robotham - Chief Engineer} III LeC.5060 Insulated Thermometer. The average oil consumption for the mileage was 1341 m.p.g. There was a gradual fall towards the end of the mileage, but this was chiefly due to leakage from the front and rear of the crankcase. At no time did the consumption drop below 1.000 m.p.g. The bedding of the pistons was good and the rings remained free in their grooves without any undue slack developing. No piston knocks were heard throughout the mileage. The cylinder bores were in good condition and showed only slight wear, the maximum being .0035" measured 5/16" down the bore. The cylinder head was decarbonised at 10.786 miles. The desposit was low for the mileage, and uniform in all the combustion chambers. The valve seatings appeared slightly pocketed, but there had been no loss of tappet clearance during the previous 7.000 miles running. There was no necessity to re-cut any of the seatings. At the end of the running, the deposit was again small and uniform. The insulated thermometer union began to leak at 15.170 miles. The rubber sleeves had taken a permanent set in their compressed position and no longer exe(Aero Engine)rted sufficient pressure to seal the joint. It has been decided that new rubber washers shall be fitted each time the union is dismantled. | ||
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).