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).
Comparison of modifications and weights for engine and electrical components for Bentley and H'Power models.
| Identifier | ExFiles\Box 111\2\ scan0231 | |
| Date | 26th August 1937 | |
| -4- 26.8.37. TITLE | REMARKS | BENTLEY | H'POWER. Valve Gear. | This is very considerably modified. The inlet being over the exhaust. This eliminates six rockers, and push rods. At the same time bottom tappets are changed, eliminating guides etc. Rockers & push rods. | 6 off. | 5 lbs. | 2 1/2 lbs. Valves | Slightly larger. | 2 1/2 | 3 Springs etc. | Assumed no change. | 3 | 3 Bottom tappets etc. | Simplified & lighter. | 5 3/4 | 1 3/4 Rocker shaft etc. | No change. | 3 | 3 Tappet cover etc. | No change (assumed) | 2 | 2 Camshaft etc. | Considerably heavier due to a reduced no. of bearings, necessary because of cross drive distributor | 5 1/2 | 12 Drive & balances | No change. | 5 1/4 | 5 1/4 Camshaft brgs. | These are reduced in number, and changed to l/C. They are included in the c/case weight. ELECTRICAL PARTS. Dynamo. | It is hoped to lighten these items, but for the present they are assumed the same. | 24 3/4 | 24 3/4 Starter Motor. | | 23 | 23 Distributor and drive Coil | Using one only. | 5 6 1/4 | 4 3 H.T. wire etc. | No change. | 1 3/4 | 1 3/4 | ||