[blykins]

Lash grows when hot.

It seems counter-intuitive, but that's the way it works.

You have a cold lash setting and a hot lash setting. On a first fire-up with an engine that has an iron block and aluminum heads, I'll set the lash about .006" tighter when it's cold. For instance, if your cam card reads .016/.018" hot lash, I'll try about .010/.012" cold. It's usually pretty stinkin close.

You can manipulate lash a little bit to change the operating characteristics of an engine. Tighter lash will make the engine think it (effectively) has a larger cam. This can raise the peaks a little higher and shifter the curve to the right. Conversely, if you loosen the lash, the cam "gets" smaller.

On spring pressures, you want enough to control the valvetrain. If you use a lot more than that, horsepower can be used up in compressing the spring and you cause unnecessary valvetrain wear. You wouldn't use 750lb open pressure on a Comp Cams street roller grind that never sees anything above 6200.

Spring pressures are based on rpm and the weight of the valvetrain components. If you're running titanium valves, retainers, and locks, then you can get away with less pressure.

No real magic formulas. If I have a GOOD relationship with the cam grinder (we're not talking about Comp Cam's tech line), then I will go with their recommendations. Otherwise, it's experience, logic, and a little salt thrown across the shoulder.

The idea behind the beehives is that they are small and light, the equivilent spring pressure needed for a set valvetrain is a lot less. They are great for hydraulic roller camshafts and flat tappet stuff. I wouldn't feel comfortable with a set on solid roller stuff.

Hope that answers your questions.