Hello. I've read through some threads I searched for and can't find the help I'm needing. I was attempting to remove an old stem and put in a new one into the shimano 600 headset, but realized that I wanted to make sure I wasn't getting myself in too deep before I did so. After I couldn't get the installed stem out, I decided to give up for the night and try to adjust it back to how it was before I began messing with the stem. Now, I cannot get the steering loose enough without the fork and stem being loose in the head tube and when I tighten the headset bolts a little more, to where the fork and stem are snug in there and not loose, the steering is really tight? How can I adjust it back to how I had it, where the steering was smooth and everything was secure, snug and tight? Any advice or help on this would be greatly appreciated! Just the regular hexagon shaped shimano 600 headset is what I have. Thanks!
Getting your stem out has nothing to do with your headset adjustment. You do not need to undo the headset to remove a threaded stem, just loosen the bolt on top of the stem and pull. I suspect yours might be rusted in place, based on your description, and there are several remedies for that. Search "stuck stem" or the like.
Now that you've loosened your headset, however, you need to reset it. Here are Park's instructions for heaset adjustment - scroll to the adjustment paragraph. Hope it helps.
There's a very important step to removing a quill stem that is sometimes overlooked: after you back out the stem bolt a good amount, you have to hit the bolt down with a hammer/mallet to disengage the wedge; you don't just pull it up after the bolt is loose.