[Steve C.]

Cliff stated- "I contacted a cam designer, who told me specifically that the seating velocity is simply too fast, and can and will cause troubles at high rpm's."

And this from a recent magazine cam article within the subject about valvetrain inertia as a whole....

"Hopefully the mass of the valvetrain and high spring pressures allow the lifter to follow the cam all the way down the ramp. If not, the lifter will bounce, which kills the valve seat and sends harmonics that destroy the springs as well as the needles in roller lifters. This reduces the volumrtric efficiency of the engine, as the valve doesn't seat properly and robs horsepower."

You must design the entire valvetrain to work as a single system. The problem is that the weight of all the parts, the elasticity of the components, and the effects of the springs all work against the cam motion at high rpm.

[Skip Fix]

I was mentioning UD cams for similar short seat duration but the same 0.050 as the crower/041. Since the XEs may have problems why not use some UD lobes?

I used one XE in my TAs original motor when I freshened it a few years back. A custom one 262/270 on a 112 LS. I was not impressed much either and never got a valve tick out of it, the seat duration was longer than Comp said even at their own lobe lift. Similar motor with a Sunnit 2801 runs better.

[Murf'sDad]

Here's a UD cam for you. But I'll be running it with solid roller lifters lashed at about .008".

FWIW, Stewart