Terry, a thoroughly good book on the Lotus Twin Cam engine by Miles Wilkins, published in 1988, by Osprey Publishing Limited, 59 Grosvenor St, London, W1X 9DA, possibly out of print now, try some secondhand bookshops, the I.S.B.N 0-85045-676-2, worth every penny, but then I bought mine back in 1990, sorry won't part with it, but could send info if you let me know what the cams are that you have, e-mail if you want, glad to be of assistance, regards Nigel, in New Zealand.