You can't just assemble the engine and then turn it over by hand to check valve clearances. The lifters won't be pumped up fully. You need to take a couple of old lifters and modify them to be solid. first you take the retaining clip off of the top of the lifter. You just use a pick or small flat tip screwdriver. Then remove the "cap" that the pushrod sits in out and set it aside too. Dump the guts out since you won't be needing them. Then you put some washers inside (I used 3/16" that I found on a shelf in a pack of 100) to fill up the space that is left from the removed parts. Put the cap and clip back on. You don't want any give in the lifters. Then you place a little bit of Play-Doh or something similar on top of your pistons so that the valves will press in on it. Install your solid lifters and roll the engine completely over after the heads have been installed and torqued down and you install pushrods and torque down the rockers. I just used the head bolts for this. When you've done all eight cylinders, then you remove the heads and measure the thickness of the compressed Play-Doh to get an accurate valve clearance reading. I don't know if it's needed, but I first sprayed some lube (WD-40 or similar) on the tops of the pistons and the bottom of the heads so that the Play-Doh wouldn't stick. Then I waited until the next day to make sure that the Play-Doh was dry so that it wouldn't compress when I measured the thickness. I didn't particularly enjoy modifying the lifters so I only did two. That way I could use two pushrods and move them and the pair of rockers around the cylinders. This is kind of a pain in the back side, but it's worth it to know that you have the valve clearance. Typ4 says that you want at least .030" clearance.
