How Valve springs are checked
I had to check the valve springs for a 4G63T
This is a simple process. But a specialized piece of equipment is needed.
I use a Rimac spring tester with a 300lbs scale.
The first thing to do is set the stop to the correct height.
The spec used is 66lbs @ 1.575
I find that a venier caliper is more accurate than the built in scale.
Place the spring to be tested in the spring tester
Compress the spring to the pre set height and read the pressure.
It is a quick and simple way to have your valve springs checked to make sure they are in good serviceable shape.
Low spring tensions can lead to a lazy rev of your engine and also valve float.
Most of the valve springs I tested I found to be well out of a usable spec.
Most springs I tested fell in the range of 40-55lbs @1.575
Most spring manufactures allow for 10% loss of spring pressure for spring break in.