question on a valve spring problem

Valve Springs / Camshaft Profiles

The spring tail issue is the symptom, not the cause. When valve surge occurs the spring actually leaves the spring and spring retainer at the same time. At that point in time there is no valve spring pressure. With that said, we can see that excess spring pressure not an answer. It may work in some applications, and will always be the short term approach. No matter what the installed pressure is, when valve float occurs the spring pressure is very close to “0”
The efforts of the spring suppliers in the last several years, has been to increase the frequency of the valve spring, which postpones the point where spring surge occurs, in relation to engine speed. This works very well and in my mind has been the biggest step forward in spring technology in 20 years. This, by itself, may only hide the symptom ( spring tail breakage),and most of us will just put the problem out of our minds. Out of sight, out of mind.
I feel the majority of the problem is in the way we place the valve on the valve seat.
We can approach this by adding strength and rigidity to the entire valve train. This includes the cam shaft core diameter, roller tappet body diameter, pushrod diameter, rocker arm (mass), rocker shaft (material and mass), rocker stand or girdle (material and mass). Any of these improvements will help improve the end result. As we do this the result will be a combination that will show improved valve control in our working range, and in most cases no further work appears to be needed.
To go further, which we feel necessary, the camshaft seating velocity must be slowed as the valve train is stiffened. I feel the text from here should be turned over to John Partridge from Bullet Cams, and Chase Knight from Crane Cams.
There is a major amount of valve train control and high RPM stability to be gained from where we were a year or two ago.
I would ask John and Chase to continue on and fill in the blanks.

To answer the rest of the question: No, trimming the tail makes no change in pressure. You will be trimming a piece of a spacer coil away.

Thank You: Noel Manton
Tel: 951: 674-2212
www.mantonrockerarms.com
www.mantonpushrods.com

 

I thought that shimming the springs .050" from coil bind helped with the unloading of the spring as it approached valve float as well as the dancing around of the spring? I agree with you on the opening/closing rates of the camshaft, as well as the valvetrain rigidty.