Lift for '62 406 is .500 at ZERO valve lash. Valve springs cannot possibly have less than 200 lbs at full open. There were 2 springs in '60, early and late. The early ones were totally inadequate and are listed 94-104 closed and 180-198 open. These were out only a short time before new springs were released. Vlave float set in early with these springs. They were changed to 80-90 closed and 255-280 open. Same tension requirements for 406 as well. From the Steve Christ book, "How to rebuild your Big Block Ford.
