suggestions of what to do with the car: valve seals shouldn't be too hard to do. I've only opened 1 or 2 honda heads but if you can get a spring compresser on the valve springs, doing the stem seals is a piece of cake. also, recheck the valve clearances and double check that you had the engine at the right place when you did the leakdown test. If we were closer I'd offer my help fixing it.
So, I take it this can be done without pulling the head? Any tricks on avoiding dropping the valve into the chamber or is that not a major concern if done carefully?
I initially had slightly misaligned things on my first leak-down attempt so I understand what you're referring to. Got something like 60% leakage! After settling down and realizing that couldn't be right (I hoped!) I figured out I had to actually remove the timing belt housing to be sure where things were. Got consistent results after that.
So, I take it this can be done without pulling the head?
Yes. The valve springs are in the way (thus the compressor to remove and reinstall them), but it's quite possible.
Originally Posted by Darkelf
Any tricks on avoiding dropping the valve into the chamber or is that not a major concern if done carefully?
There's two approaches to it. The first is to apply air pressure to the combustion chamber to hold the valves shut once each spring has been removed. As Erik said, you need an adapter that threads into the spark plug hole which lets you connect that cylinder to an air source, and obviously an air source such as a compressor.
The other approach is a bit more shade-tree, but works just as well, if not better: Thread several feet of nylon cord (the woven-case kind that doesn't shed little bits of plastic) into the cylinder though the spark plug hole, leaving a bit dangling out so you can remove it afterwards. Rotate the engine by hand until the piston travels up and presses the pile of cord against the valves, holding them closed.
Both methods should be done after the rockers have been removed.