The one you show is when the head is off. It has to reach around to the large end of the valve to work.
There are valve spring compressors that look like oversized battery terminal removers, are the best to use. They have a set of jaws that grab the bottom of the spring and a hand screw that pushes down from the top. Those are the only ones that I will use while using compressed air to keep the valve in place.
The lever type does work, but it is very easy to push down on the valve and loose the compressed air in the cylinder. However there is an old trick to use them.
This is going to sound very ghetto, but does work. You are going to have to remove the rockers and spark plugs anyway.
Get about 5' of soft clothsline, yes clothsline. The soft cottony kind. With the spark plugs out it should be easy to rotate the engine around by hand. One cylinder at a time. Lower the piston on the cylinder that you are working on. Coat the clothsline lightly with oil. Through the spark plug hole, fill the cylinder with the soft cloths line and leave about 6" out to retrieve it when done. "By Hand" turn the engine until the cloths line pushes up on the valves. You'll feel it. Now you can use the lever type compressor to push the spring down. If the valve moves down with the lever too far, back the cylinder down and refill with the clothsline. It is normal for the valve to move down about 1/4" untill it compresses the clothsline some. The clothsline just keeps the valve from falling into the cylinder and being soft, unless you are abusive, doesn't damage the valve. When finished with valve springs and valve seals while you are there, reinstall the keepers, back down the piston and remove the clothsline. Next cylinder. Yeah, by the way, make sure you have one of those little magnet pocket screwdrivers. Make working with the keepers much easier.
[This message has been edited by cmechmann (edited 03-13-2016).]
