Specification for J.1. model covering the engine, flywheel, gearbox, mounting, and camshaft.
| Identifier | ExFiles\Box 5a\1\ 01-page149 | |
| Date | 21th May 1931 | |
| SG. {Arthur F. Sidgreaves - MD} HS. {Lord Ernest Hives - Chair} } FROM R. {Sir Henry Royce} X8770 R2/M21.5.31. BY. {R.W. Bailey - Chief Engineer} ___________________ C. to NOR. O. {Mr Oldham} J.1. SPECIFICATION. A. {Mr Adams} 5770. C. to RHC. {R. H. Coverley - Production Engineer} HY. {Tom Haldenby - Plant Engineer} X. 5090. ENGINE. 3.25" X 4.5" - same as 25HP. - no change to crankshaft dimensions, but to have big crankpins, 8 balance weight scheme, 6 units, and con. rods for large pins. FLYWHEEL. Flywheel of the lighter stiffer type but sufficient inertia to give freedom from sideshaft rattles - i.e. tested with black sideshaft gears. The big pins with balance weights reduce the risk of flywheel flutter. GEARBOX. Gearbox to be longer to allow for double helical with syncro-mesh. (no clutch brake because syncro-mesh friction clutch acts as a clutch brake.) ENGINE MOUNTING. Engine mounting to be fore and aft Trunnions with torque reaction dampers as far forward as possible, and soft unloaded rubber to give the engine its position. In this case we fear the feet must be near the dash but we should prefer that they were far forward. It may also be found some advantage to chassis steadiness to have damper or rubber feet at the gearbox end of the unit: this will be known at an early date. CAMSHAFT. At the end of the year 1928, we went deeply into camshafts and sent diagrams for new ones which do not appear to have been adopted. It was reported that the test results from these camshafts showed insufficient gain in power when used without any other change being made to the engine. These lobsided cams are for ultra efficiency of opening and valve spring life. The inlet valve is larger in dia. but lighter than the exhaust, and is subject to the inrush of air. We think it less confusing to refer to cam timing with following clearance: CAR WORK - - - .013" AERO WORK- - - .025" This is the beginning of the rapid acceleration so that the long quieting foot of the cam does not enter the problem. You could have two camshafts (see diagrams of openings) i.e. the one given by WW. in 1928., Lecs. 1153 and 1158., and a new one using this exhaust as inlet; 61 divisions, and a new exhaust of 63 divisions, (designed on Lec. 1158. ideas.) BY. {R.W. Bailey - Chief Engineer} will kindly see to this. We do not propose altering the height of the lift. | ||
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).