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).
Weight comparison of components between a standard 4¼-litre Bentley engine and an O.H.C. converted engine.
| Identifier | ExFiles\Box 113\5\ scan0187 | |
| Date | 28th January 1937 guessed | |
| ENGINE WEIGHT. COMPARISON BETWEEN THE PRODUCTION 4¼-LITRE BENTLEY ENGINE AND THE OVERHEAD CAMSHAFT CONVERTED ENGINE. PART STANDARD ENGINE WEIGHT IN LBS. PART O.H.C. CONVERSION. WEIGHT IN LBS. Standard engine with starter motor & exhaust manifold (no gearbox) 588.5. O.H.C. Conversion unit with starter motor and exhaust manifold (no gearbox) 575.5 DETAIL WEIGHTS. Cylinder head (before fitting studs, valves, etc.) 66.0 Cylinder head (with all inserts fitted, but no studs and valves.) 37.37 Inlet valve .21 Inlet Valve .2 Exhaust .22 Exhaust .25 Total weight of set of 12 valves 2.37 Total weight of set of 18 valves 4.19 Valve springs (12 off) 1.62 Valve springs (36 off) 7.31 Camshaft 5.5 Camshaft .44 "" bearings .78 "" bearings .78 Tappets 2.81 Driving Sprocket .78 Push Rods 1.5 Driven .78 Bridge Pieces .72 Cam Wheel 2.72 Rocker Shaft & Rockers 6.12 Chain 1.62 Cam-wheel & cam balancer 5.25 Rockershaft & Rockers 12.12 Tappet Guides 2.37 Camshaft Housings 10.15 Studs (Cyl. to crankcase) 5.41 Oil Pipe & Unions 1.0 Oil Pipe & Unions .5 Drainpipe (Oil.cyl.hd.{Mr Hayward/Mr Huddy} to crankcase) .5 Wheelcase 5.75 Wheelcase 8.56 Chain tensioner .56 Camshaft flywheel 2.25 Rocker Cover 5.56 Rocker Cover 9.94 Induction Pipe 5.0 Induction Pipe 4.72 Exhaust Manifold 8.12 Exhaust Manifold 12.94 Cyl. block 66.94 Cyl. block 72.94 Pistons 7.12 Pistons 7.59 | ||