A tip when you reassemble (from my upcoming book, "Performance" chapter):
In your first picture of the top end, it shows the K3 and later style rocker shafts with the 2 tiny 5mm bolts on each rocker shaft that locks it in place. This late-model mod by Honda costs HP and wears the rocker shafts very quickly, because the oil grooves in the rocker shafts seldom lined up with the oil holes in the rockers. You can change this and recover the HP and greatly extend the life of the rocker shafts (presuming you do NOT buy Honda's current rocker shafts) with the following steps:
1. Remove the eight 5mm bolts and throw them in your spares.
2. Assemble the rockers on the shafts in the cam towers and snug in the middle mounting bolt. Slide the rocker shaft to the left and right, as shown in the pictures below, and check to see if the oil groove is still visible through the oil hole(s) in the rocker(s). Chances are, not when at one extreme or the other (sometimes not even when the shaft is centered!).
3. Elongate the oil hole(s) as needed (as shown in the pix) with a tapered grinder stone, so the oil groove is always exposed to the oil hole. Usually this involves opening the hole toward the rocker's backbone ridge.
4. When reassembling in the final buildup, install one of the little 5mm bolts temporarily into one of the holes as a "handle" to let you turn the shaft back & forth while torquing down the long center bolt. This bolt should only be tightened to 7 ft-lbs, BTW: not covered in most manuals. When tightened down, make sure the shaft can still rotate, testing it with the little 5mm bolt handle. Then remove the 5mm bolt.
This process allows the rocker shaft to rotate while running, which distributes the wear and oil, and reduces friction.
One caveat: if you have a high-lift cam and are worried about breaking the rocker shaft and having the pieces slide out, consider just Loctiting the 5mm bolts into position, but not tightening them. At the same time, open up the rocker tower's holes so the shaft can at least rock back and forth a little bit.
Honda's current replacement rocker shafts have half-moon-shaped center "grooves" where the longer bolt goes through to hold the shaft in place. This does not allow for rotation of the shaft at all. And, the last new shafts I saw did not even have oiling grooves underneath the oil holes in the rockers! If you get new shafts, I recommend grinding in your own oiling grooves at least, and grinding the center groove all around, as well. If you go out and buy some 12.00mm Thomson shaft, which comes in 12" long pieces, you can make your own, sans 5mm holes altogether like the K0-K2 shafts, for a lot less $$.
