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).
The initial test and performance of the J.3 engine unit, including details on general performance, power, and camshaft settings.
| Identifier | ExFiles\Box 179\2\ img266 | |
| Date | 19th February 1932 | |
| SECRET. ORIGINAL. To R.{Sir Henry Royce} From Hs.{Lord Ernest Hives - Chair} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} c. to By.{R.W. Bailey - Chief Engineer} REPORT ON J.3 ENGINE UNIT. K5770. The first J.3 unit was received on test on 17.2.32 and after running light for some time was opened up full throttle we attach herewith power curve. GENERAL PERFORMANCE. The general behaviour of the engine was exceptionally good and no trouble was experienced throughout the whole running. The ventilation holes in the flywheel caused a considerable amount of humming so that it is difficult to say whether the engine gears are noisy or not. One could observe that there was a definite deflection on the overhang rockers. The brackets for holding the rocker shaft will most probably have to be spaced differently. The tappets were not as quiet as we should like but this may be attributed to the flexing of the rocker shaft. The only other noticeable fault was a noisy oil pump. POWER. The engine was fitted with two single J.3 type carburetter: but the development work on these carburetters has been carried out on a J.1 therefore the choke size will be on the small side for this engine. The compression ratio is 5.9/1. The B.M.E.P's are practically identical to those we obtained on J.1 unit if we make the necessary allowance for compression ratio and slightly higher depression. We anticipated that we ought to obtain 120 HP. so the fact that we have obtained 117.5 shews that the engine has come out remarkably close to anticipated results on the first run. CAMSHAFT. The camshaft should give the same valve timing as E.57177, 110° as used on Japan 1. The valve timing as checked with .020 clearance was :- I.C. 1.7° A.T.D.C. E.O. 43.3° B.B.D.C. I.C. 31.4° A.B.D.C. E.C. 1.7° A.T.D.C. | ||