Either something is out of time like Mirada said, or you might be seeing what happened to me when I did my 2.7 chain: Apparently there was carbon buildup in the cylinders. The carbon absorbed moisture and swelled, creating an interference that wasn't there before I did the work. In my case, the moisture came from compressed air that I used to hold the valves up while I replaced the valve stem seals (I didn't have a water trap on my compressor). To fix it, I injected a measured amount of Sea Foam into each cylinder thru the spark plug hole and let it sit for a while, then sucked the Sea Foam and dissolved carbon out with a clear plastic tube taped and sealed onto the end of my shop vac hose and inserted thru each spark plug hole. Then I repeated putting Sea Foam in each cylinder and sucking it back out. The Sea Foam was totally black the first couple of times I did that. I kept doing it until the Sea Foam was pretty clear - about 5 times IIRC.
Ordinarily I'd be skeptical about moisture causing carbon to swell in your case since you didn't add moisture into your cylinders like I did. However, I get the impression you bought this not running, so maybe it's been sitting unused for quite a while and slowly absorbed moisture from the air?
There is a third possibility, and that is that something fell into or got dropped down into a cylinder thru the spark plug hole.
Whatever you do, don't force it to turn past the stuck point.
Critical question: Had you turned the crankshaft before you put the cams back in? If you did, and it turned OK then, then it's not a problem with carbon having swelled from moisture.
You'd probably hate to do this, but you could remove the chains and cams again, and if, with the cams out, you can then turn the crank all the way around without problem, then you know it's a cam timing problem and *not* carbon or some object in a cylinder causing the problem..
'98 LXi - Later Concorde gages (black w/ chrome rings)/'99 LX - LHS gages (white) - HIR bulbs
Last edited by peva; 03-23-2012 at 10:11 PM.