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).
Cylinder re-grinding, piston fitting, clearance measurements, and engine performance tests.
| Identifier | ExFiles\Box 35\2\ scan 017 | |
| Date | 16th February 1916 | |
| - 2 - Before fitting these pistons the cylinders were all re-ground, in order to make them all equal, - they were actually .015" oversize. This was Commander Briggs' request; he also made the request that the proper record be kept of the cylinder and piston sizes, so that after further running he would be able to know exactly the amount of wear which took place on the cylinders and the pistons. Before finally building up after the last inspection, the cylinders and the pistons were again finally measured up and recorded, and the actual clearance was found to be about .010" across the body of the piston, and .008" at the mouth of the piston. We cannot say the engine is now entirely free from piston knocks, and they are certainly perceptible when the engine is started up cold as with 49GB, but when the engine has once got into its normal state as regards heat it is quite free from piston knocks, and it is certainly much more satisfactory than either 7CA or when this engine was fitted with Zephyr type pistons. The H.P. of this engine was particularly good when it returned to the Works, and had the advantage of maintaining it at high engine speeds, and according to dynamometer tests the H.P. at 1750 revs. on the road wheels was 60 H.P. and at 2,000 it was 62 H.P. The average L-E type car gives about 58 H.P. at 1750, and about 55 H.P. at 2,000. | ||