Wow...I just found this, and am humbled, honored, and even a little embarrassed by everyone's support.
Thanks to you all!
And, I've made mistakes before, but this isn't one of them...
To the original problem:
Groover: there's only one thing I know of that can cause the wasp-waist to get grooved like that: one or more rockers had to be seized (or dragging) on the shaft enough to force it sideways into the bolt body, and there would be a corresponding witness mark on the bolt to confirm it. There will also be witness marks where the rockers have done this grab.
To cause this rocker seizure, all that must happen is a lack of oil pressure in the rocker's oil passages. This can be caused by the following things, some of which have already been mentioned above:
1. One or more missing O-rings underneath the cam bearings. There are 4 of them, and in the post-1970 engines (where the 5mm bolts are found) they are all 6x2mm in non-Honda size, or 5.9x1.9mm in Honda's parts. If one is missing on either cam bearing, it takes less than 1 minute to finish off the cam bearings, 2 to wipe out rockers, and less than 5 to rip up the cam.
2. Sealant from the cylinder base gasket area or the head gasket (if used in the 2 inner oil port areas) blocking the .033" oil strainer holes in the oil jets. Both the pre-1971 and post-1970 engines used these strainer holes to protect the .035" oil jet hole from being plugged: in the early ones there are 12 such strainer holes, the later ones have 7. Silicone sealant and Permatex-like sealants can do this to you, so I recommend against using them (in my book).
3. The above-mentioned mis-set locating dowels issue with the cam bearings.
4. No oil pressure, from a pump that has the dreaded air bubble in it. If the engine sat upside-down for more than a couple of hours with the oil ports open on the side of the engine, this often happens. The only way I know of to remove it is to set the pump in about 2" of oil and spin the gear back and forth until it geysers oil out the feed port, where the check valve has to be pushed open to let the oil pass. For this reason, startup ALWAYS require an oil pressure check at cranking speed before letting the engine run.
I'm sorry you've had this mishap, but I think with a little sleuthing you will figure out what went wrong. It's not like I haven't done it, but at least it was many (too many?) moons ago when I did it myself, else I would not have known how it can happen.
Other questions:
1. Is your cam stock? Cams with lift of more than 8mm require use of the 5mm bolts, which is noted in the book. This is for those days when pistons and valve meet after the missed shift, or when the valve springs bind from not being properly shimmed at setup.
2. What is the valve lash setting(s)?
3. Is the cam timing within 8 degrees of stock TDC reference? If it is more than 20 degrees off, the pistons and valves can meet at pretty low RPM, which will make lots of noise.
4. Screeching sounds indicate loss of lube somewhere (in bearings, perhaps?), or something like chains dragging against metal. See if you can locate those witness marks? If the engine was run for only a few minutes and metal powder showed up in the pan that fast, it could be coming from a chain dragging something, or from the rod bearings, even crank bearings, if no oil PSI showed up. For filings from a damaged rocker shaft to show up, it would also be in the oil return passages from the head, down the cylinder drains, and would be all around in the cam area. If it is just in the bottom, it can be from the cam or primary chains, or the crankshaft.
So, take a look around, maybe we can help you find it?
By way of reference: my 750 has 140,000+ miles and 40+ years on it, without the 5mm bolts. It still has the OEM rocker shafts, and they are worn less than 0.0004" in the worst spots, with no shiny spots in the wasp-waist areas. This is, at best, an interesting mystery?
