Cast Aluminum Timing Chain Cover Vortec/small Block Chevy Cast Aluminum Timing Chain Cover HolleyHolley now offers a solution to the plastic OEM timing chain covers on 1996 up Vortec Small Block Chevy engines. Our cast aluminum timing chain covers are an excellent upgrade from the OEM part, offering the superior durability of an aluminum part with improved functionality. These cast aluminum covers feature timing indicators molded into the body and are available with or without a crank sensor provision to accommodate both carbureted and EFI