The most accurate method on hydraulics is with the engine running. Setting them without running is OK to get it to start, but it should be running(and at operating temp) for final adjustments.
There are clips you can put on the rockers to keep the oil from splashing all over, or, if you have an old valve cover, you can cut the top off of it, and bolt it on with a couple of bolts. This will help save you from making a mess, too.
Remember when adjusting hydraulics, when tightening them down, do it slowly...this will allow the lifter to properly "bleed" off, without killing the cylinder.
Also, don't press down on the rocker/ratchet while tightening the nuts, as that can effect the adjustment if you're listening for the "tick" to go away...
Adams' Apple2009-08-08 20:12:10

I think I'll call around and see if I can find a spare set of valve covers. I had an old set of ugly chrome ones and I threw them away. Never fails...as soon as you need something.

The valve cover will help keep the oil in the head, but they won't really help keep it from spitting out the ends of the push-rods...that's where the clips come in handy. I have, in a pinch, used some cardboard, and laid it up at the tops of the rockers, to help deflect some of the oil.
I do have a set of splash clips, tho. You might even be able to find some at a parts house.

I'll check around and see if some of my friends or maybe even O'Reilly's have some clips. I just hate to get oil all over my engine compartment. I think I have located a pair of old valve covers I can cut the top out of. My first car was a 56 ford F100 pick-up. I put a Boss 302 engine in it and it had the factory solid lifter set up that I had to adjust about once a month. I always hated the oil mess.

If you cut the top off of the valve cover, it helps with oil leaking at the gasket rails but you still have to run the clips it still throws oil from the clips, rocker balls and rocker tips, because  the rocker on a small block are in a row, I cut a slot front to back in center line of,  the rocker studs just wide enough to get the socket in on the rocker nuts, didn't have to run the clips very little oil splater, stood on top of it with a towel, BUT because your BB has the "porkey pine" valve arrangement you would have to cut seperate slots for the intake and exh valve of each cylinder at stud centerline which are angled, its going to take more time for layout and you will probley have to remove the pve baffle but what the lleh, might want to have two valve covers just in case you mess up, remember centerline of the studs not the valves like I did....anips2009-08-10 14:38:45

I used to have a set of valve covers I actually drilled holes in right over the rocker studs,one for bb and one for small blocks. Worked great, but it was a wee bit hard to actually hear the tick-ticking like that. Don't know what the heck ever happened to them....
I have found that the clips that I have work well to keep the oil from splashing out too much. I use the clips, and run a piece of cardboard down the bottom side of the head to keep the oil from running out on the ground. As long as the idle is right, and I don't wing the throttle (), I don't make too much of a mess!

the hole idea is even better, layout would be a bear but if you got the first one right and had an adjustable square, not much room for a mistake, but it can be done for a big block, supprised no one has come up with a commerically built one, joel you mean you don't have a "bionic ear"in the tool box, BB's are noisey you can adjust all day long and you still hear em in a vette, it might be easier just to install side pipes.... anips2009-08-10 20:14:34