Chevy Smb Double Roller Timing Set. Application for flat tappet cam, 262-400 first generation smb engine. Includes steel cam & crank sprockets, true double roller chain and instructions. The cam sprocket is a 3 bolt design while the crank sprocket is machined with three keyways--4 deg advanced, standard and 4 deg retarded. Teaming with a rugged true roller chain that has a solid bushing design to help eliminate chain stretch. This set will give more accurate timing and longer life at a good price.