How Does Installed Height Affect the Spring Tension?

Installed height is the determining factor of what the valve spring "Closed Tension" will be. The camshaft specification card, and the spring section of the catalogue both show what the approximate tension a particular valve spring will exert if installed at a specific height. For example, spring part no. 99848 shows 105# @ 1.700". This means that if this spring is installed at a height of 1.700" it should exert 105 pounds of tension with the valve closed.