I have asked this question before, and got one answer, but I want to ask it again, now that I know a little more about what I am asking about. I have a '79 casting 460 block out of a truck, am bolting up some '73 linc. casting heads that have been fitted with crane cams springs and retainers. I have been unable to find any numbers on the springs. The crank is stock, and so are the rods, but I have fitted aftermarket Speed Pro flat crown pistons onto them. My question is, with a rocker ratio of 1.73, what would be my safe lift on a cam? I really don't want to smash valves, after I have put so much into this engine. I have been told that anything around .500 lift would be safe. I see that there are some seriously wicked cams available, with massive lift. and I know lift is where your power comes from. I am looking at a .485 intake, .504 exhaust cam, will this cause a problem, or is this going to be mild enough? I wish I knew more about what I could run safely, any help would be great.