Right, next-day follow up post.

I checked all valve clearances again last night, A-OK. Cams are in sync with the crank (the TDC mark is some *tiny* fraction of a degree off).

The H-A.net archives show that bearing caps can make awful noises if they're unhealthy. I went in this morning and pulled the cam holder and bearing caps for the exhaust cam.

Everything looked pretty much right. I re-installed exactly the way that I had before: cleaned the bearing caps, put fresh clean motor oil on the bearing surfaces, put RTV/Hondabond on the edges where the caps cross the head edge, torqued all bolts in quarter-turn increments plus in the official sequence, torquing the big bolts to 240 inch-pounds, the small ones to 86 in-lb.

Will do the intake cam next, then close it up and start it.

The only thing which I noticed was that the belt-side exhaust cam bearing cap was slightly reluctant to drop back in place. The cap on the other side went right back on. The beltside cap went on slightly angled. One side sat flat, the other was raised 1mm or so. I lifted it off and straightened it and tapped gently with a mallet and it then sat flat on the mounting surface.

Something similar happened when I put that one cap on the previous time. Hmmmmm. The cap might be distorted, or the dowel pins underneath it may be slightly bent.

Or, there might be a possibility that my low-range torque wrench is somehow wildly out of spec. I store it at zero and don't use it as a breaker bar, so I doubt that.

C