This is a repost from the engine tech forum, but I haven't had a comment in a week, so I'm hoping its an Integra-specific problem that someone here will be able to crack.

So I've had this noise from my engine for awhile... familiar to anyone who's read my threads before. I take the car to one of the better shops around, and they tear it down a bunch of times, come up with all sorts of theories. There's an inconsistancy though. They check the bearings, find two switched caps, switch them back to normal, and the noise is still there. They find an oil jet hitting a piston, so they take it out and the noise goes away (but oil gets everywhere and the pressure drops dramatically). They put the jet back in but turn it so that it doesn't contact the piston, and the noise comes back. The guy then checks out my pistons and notices that there is no lower skirt. Basically the upper skirt and where the rings are is the only place the piston is contacting the cylinder. The Wiseco pistons I have don't have the skirt, although most JE pistons and others do. The shops buys off on the theory that its piston slap at BDC, when the bottom of the piston clears the bottom of the cylinder. I get sold on it too, until I get the car home.
What was once tapping is now a rattling (like marbles in a glass jar) when I step on the gas. When I let off of the gas it goes away. Also when I first start the car up, for about 15-30 seconds it goes away. I then remembered that the guy said my oil pressure went very low with the jet removed. Now, these three events (jet removed, decelleration, starting up) all have something in common... low oil pressures. What I'm trying to figure out though, is what in the engine would rattle with normal oil pressure, and not with low? I could see the opposite being true... a rattle with low oil pressure, and when everything got lubricated, it going away... but not this way.
Am I just sort of throwing darts on this one, or does any of this sound feasible? Better yet, has anyone had this problem before? Let me know your ideas on this, they'd be much appreciated.

Subsequent post:
Possibly related to missing a head oil control orriface? I was looking over the Helms manual today for all the pieces and parts involved in engine lubrication, and I don't remember ever seeing this little guy when we put the engine back together. A shop had the head off too, and I would think they'd catch something like that... but then again.
I know the intake and exhuast rocker shaft orrifaces are in place, simply because we went to extraordinarily tight security with them.