Abstract: A tool kit is provided for repairing the snap ring grooves of a cam follower bore in a diesel engine cylinder head without removing the cylinder head from the cylinder block. The tool kit includes a cutting tool which will both enlarge the cam follower bore to allow the use of an oversized spring retainer and cut an enlarged snap ring groove to allow the use of a more substantial plate-type snap ring. A snap ring installation tool allows for easy placement of the snap ring in the cam follower bore. A concentric wrench having concentric yet independently movable sockets for quick valve and fuel injector clearance adjustment is included.