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 component testing, detailing valve wear, induction system comparisons, and performance notes.
| Identifier | ExFiles\Box 83\1\ scan0244 | |
| Date | 10th October 1936 guessed | |
| ( 5 ) VALVES & FITTINGS. LOP EB.2708. Existing complete to above LOP incorporating:- 3 - EB.2970 Exhaust Valves KE.965 Stellited Nos.1,2, & 3 Cylinders - Standard Clearance. 3 - EB.2970 Exhaust Valves S/SLV Stellited. Nos.4, 5, & 6 Cylinders - diametrical clearance. between Valves & guides .0015" - .002" 6 - EB.2793 Inlet Valves - S/SLV diametrical clearance of .0015" - .002" in the guides. RM.{William Robotham - Chief Engineer}53 Valve Springs - not enamelled. The compressions were poor and uneven when the car was taken over. The valves were ground in at 10.786 miles after which the compressions were excellent for the rest of the mileage. Examination of the valves at 10.786 miles showed that the necks of the KE.965 were more deeply scaled than the necks of the S/SLV exhaust valves in each case. The seats were uniformly burnt, but not deeply. There were no signs of picking up on the valve stems, and there was no visible difference between the state of the KE.965 and S/SLV stems. The inlet valve seats were pitted but not deeply. Ordinary grinding-in gave a petrol tight joint in every case. During the rest of the running, tappet clearances have been practically unchanged. INLET PIPES. LOP EB.2703. Existing, complete to above LOP - Standard Production for 3.1/2 litre engine. CARBURETTER. LOP EB.2705. Existing, complete to above LOP - as standard production for 3.1/2 litre engine. These are standard 3.1/2 litre Bentley parts, and comparison tests against standard 4.1/4 litre induction pipes and carburetters fitted temporarily in place of the above showed no preference for either induction system except a personal impression of sluggishness picking up in top from 10 MPH. with the larger pipes. Acceleration figures however show no difference, and there was no gain in maximum speed with the large system. It was found that the water pipes which enter the cylinder head were too long and fouled the casting. They were reduced from 1.33" to 1.2". Carburation was good in all respects and no ill effects were experienced during hot weather with air temperatures of 32°c. Idling was excellent throughout, except for short periods directly after prolonged full throttle work, when it was a little irregular. | ||