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).
Letter to Rover comparing camshaft toes on Bentley and Cadillac engines.
| Identifier | ExFiles\Box 127\3\ scan0027 | |
| Date | 30th March 1935 | |
| 4207? Exptl. Dept. Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson}1/KW. 30th March,1935. Captain Wilks, The Rover Company Ltd., Coventry. Dear Capt. Wilks, Thank you for your letter of March 28th. With reference to the free wheel, we should like to keep this and shall be glad therefore if you would send the invoice to me personally. With regard to camshaft toes, here is the toe on the Bentley camshaft compared with the toe on the Cadillac. You will note that on the Cadillac the valve lift increases from zero to .012 in 40° of camshaft rotation. In our experience this is about the length and gradient of toe necessary if quiet valve operation is to be obtained with an overhead valve push rod engine. Actually the Cadillac are using it with an hydraulic lash adjuster, so that the initial opening of the valve is perhaps unnecessarily gentle. On a high efficiency engine such as the Bentley, where the maximum amount of overlap consistent with good slow running is required, the toe of the camshaft is a definite disadvantage and we therefore cut this down as much as possible. You will note that on the Bentley the valve has moved from zero to .012 lift in 34 camshaft degrees. In our experience the constant velocity toe is quieter than the constant acceleration toe. If you have any other queries let me know. Yours sincerely, | ||