Edit: Byron beat me to it.
Make sure you have that cylinder at TDC when you remove the springs. You will use less rope. If you have compressed air, you can pressurize the cylinder instead of using rope, but still make sure you are at TDC. If a valve slides down into the cylinder, you get to take off the head to get it out. Once you have the spring off, use a rubber band or a zip tie around the valve stem while you work on the other one. Just remember to remove all rope, zip ties, or other things before you restart it!
