Mileage, age etc all factor into what your springs are likely going to handle. I've seen a lot of guys break a spring on the advice that they don't need to be changed. And yet..there's another whole group that didn't change and didn't have a problem.
The rub is.. what will your springs take and are you willing to bet your motor on the gamble. Because typically when a spring breaks, the valve drops into teh cylinder and gets hit by the piston. The results aren't often good....
As an installer, I refuse to install rockers or a cam w/o changing springs. I don't want to put a motor in for a guy because he took a chance on springs.
