This COMP Cams Valve Spring Kit is designed to maximize the potential of GM L31 Vortec cylinder heads when using a hydraulic roller camshaft. This kit allows up to .540" lift and provides spring rates that can handle significantly more aggressive lobe profiles. This kit has been developed to make your valve train upgrade as easy as possible by combining quality components in a package that does not require any machining! These components will drop right onto stock GM L31 Vortec cylinder heads.