The Snapon tool was discontinued a long time ago. I still have a 50 year old one, but I see them on eBay all the time. I always adjust valves with the engine running. The lever allows me to loosen or tighten the lock nut while the knob allows me to adjust the valve. This leaves the other hand free to "feel" the gap with a feeler gauge. I just can't imagine adjusting valves on a Jimmy or a Y-Block without the tool.
