Mr. Gasket Replacement Gaskets are ideal for use with quick-change timing covers, allowing you to replace the timing chain or timing gears on small-block Chevys without having to take off the oil pan. A perfect fit between the engine block and the cam-cover retainer, theyre made from a durable .031-inch composite cellulose/nitrile material and work with Mr. Gasket Quick Change Cam Cover Kits (part number 1099).