Engine Valve Spring Compressor Tool
The valve spring compressor compresses the valve springs so you can easily and safely remove the keepers and the retainer. In the picture, you see the C-clamp version which is designed to "de-spring" the engine head after it has been removed from the engine's block.
Other types of valve spring compressors are available. What ever the cost, the time savings the valve spring compressor offers makes the purchase well worth it.