The valve stem height will change when the valves and seats are ground or cut. A valve hei
FINISHING UP AND STORING COMPLETED HEADS
When all of the machine work is done, the cylinder head will be cleaned and assembled. The valves will be lubricated with a white lithium or low-fiber grease. The springs will be installed in their proper predetermined location, and possibly shimmed for pressure and correct installed height. Whenever a cylinder head is taken apart, it is advisable to use new valve stem locks and guide seals. The cylinder head may then be coated with an anti-rust spray (like a penetrating oil) and packaged in a clean, sealed plastic bag, awaiting installation. Heads can be stored, after being sprayed with oil, and sealed in a plastic bag indefinitely.
Once the installed height of the valve is determined, the valve spring will be compressed
REPLACING PRESS-IN STUDS WITH SCREW IN STUDS
Most production cast iron cylinder heads have rocker studs that are interference or press-fit into a boss that is cast into the cylinder head. A stud puller is required to remove them. The new stud is then pressed into place using either a hydraulic or arbor press and lubricating oil. Press-in studs can be converted to screw in studs by first removing the old stud and then drilling and tapping the created hole. Many try this at home with mixed success, but any machine shop should be able to accomplish this procedure without fanfare or great expense. If you plan on upgrading your springs, increasing your rocker ratio, or spinning the engine past 5,500 rpm with any regularity, you should upgrade your rocker studs from press-ins to screw in types. Otherwise, they'll probably start pulling themselves out for you.