I just picked up a set of iron gt 40 heads. I was told I didn't need anything for them. All they have is springs. No rockers or anything can I use them that way or do I need rockers. I have a stock 88 mustang gt.
The best place to get info on GT40 heads is the Fox 5.0 Tech section.
If you do not have rocker arms, the motion from the camshaft can not be transferred to the valves. No opening and closing of the valves means it does not run. The motion goes camshaft lobe, lifter, pushrod, rocker arm, to the valve.
It would be a good time to upgrade to roller rocker arms.
You will also need to make sure the springs are compatible with your camshaft. For example, the GT40p springs will float when used with even a stock HO mustang camshaft.