Hey Cylinder heads guys- advice needed

The spring rate is effected. To what degree depends on the springs rate to start with and then how much it is shimmed. Achieving the desired spring height, let’s use 2 inches, can use springs to compress the spring, seat work if there is t enough room.

At the correct spring height, the spring should have the manufactures closed pressure. If the spring height is less, the pressure goes up. If the spring height is to high, the pressure goes down.

If you had a spring pressure checker on hand, this is what you would see. It is no different on the checker to the head. This is why when people set up there springs installed height, they do it as perfect as possible. This becomes more and more critical as the springs pressures rate increases.

On a stock head and a Hyd cam, the pressures are low. Shimming the spring lower for more pressure (spring compressed more) will add a few pounds but on a very high performance engine, it may not be just a few pounds but a good bit more! This can be a huge problem if there is to much because it will grind on the cam into junk. Just the reverse, to tall of a height looses pressure and then the engine won’t RPM like it should because there is no valve control and the valve may bounce or just jump the ramps into valve float.

I’ll say it again, spring height and pressure are critical to the cam and engines performance. In a huge way! Big time. You can be off on 90 items, but the cam and valve train MUST be set up right. Failure to pay attention means a crap running low power engine.