Mr Gasket - 1183 - Fits Small Block Chevrolet with Indented Timing Cover

A camshaft button, or camshaft thrust bumper installs into the hole in the front end of the camshaft and prevents camshaft walk in roller camshaft applications. Flat tappet cams are ground with a small angle in the lobes that puts a side load on the camshaft. Without this a camshaft has a natural tendency to move or walk, out of the block when rotating. Roller cam lobes can't be ground that way so engines originally equipped that way usually use a retainer plate to secure them. The camshaft button serves the same purpose, but it does so by contacting the timing cover to prevent further movement. A worn or missing cam thrust bumper will result in too much end play, resulting in timing issues.