Valve Spring Question: Coil Bind Versus Spring Quality

I would use the 6105. Always check coil bind to see it is what the spring maker says it is. My experience is that you can check for max valve lift using a light check-er spring. When you then check again with the actual springs in place, some lift has been lost due to flexing. Going from 1.5 to 1.65 rockers with no other changes is automatically compensating with the v/springs. The higher ratio needs a slightly stiffer spring, & you get a 10% increase going from 1.5 to 1.65. You just need to check coil bind with the extra lift.