I can only read the one page that shows the .040 number so I can't comment on what the rest of it says but I will say Hughes is full of ****. I'm not the sharpest tool in the shed but I can do simple math, and I'll post it here so anyone who comes along can see what's wrong.
Hughes says the sweep pattern needs to show .040 on each edge of the valve not being rolled on by the roller. Sooooooooo, if you have a 3/8th stem valve this is the math.
.372-.040-040= .292!!!
That is a sweep of .292 thousandths. That's crazy. Beyond crazy.
If you happen to run an 11/32 valve (.342) here is the math.
.342-.040-.040= .262 sweep without correcting geometry. That's insane. You still have the same sweep, but it can't be, because you didn't make the sweep change! Just by going to a smaller valve, you have the exact same sweep, but you can't get .040 from the edges. It's impossible. The sweep is the same but the valve is smaller. In reality in this scenario, you still have the exact same sweep, but instead of having .040 from each edge, you will have only .025 per side. Am I the only one who sees how crazy this is?
Again, what if you have 5/16 stems (I use a lot of them...and the magnum junk comes with 8mm [~.317-318 diameter] so it's not uncommon)? The numbers are even more bizarre.
.311-.040-.040=.231 and yet nothing was changed! That's crazy. Again, in reality the sweep is still .292 you just have even less valve at the edge. You would be .008 from each edge with 5/16 valves.
This isn't to embarrass anyone, or make fun of what is published but that method is as ignorant as it is wrong. You need to know how wide the SWEEP is, not how much valve there is not covered by the sweep pattern. Sooooooo.....
I have a sweep of .045 on a .372 valve. Simple math says I have .163 from the edge on each side, if the sweep is centered.
I'm going to say Hughes is wrong and they should update their tech or stop publishing it. They are responsible for making people ignorant.
Hope that's not too harsh. But fact is fact. You have geometry issues. A sweep that wide is death on parts.