COMP Cams Belts - Timing, Accessory 6502 COMP Cams Hi-Tech Belt Drive Systems with Idler Gears come with an extreme application belt for high rpm and high compression durability. They feature an infinitely adjustable Vernier sprocket for absolute timing accuracy. These belt drives are best in serious street performance and racing applications. Belt Drive, Chevy SB w/Idler W /CB SNout COMP Cams Hi-Tech Belt Drive System for Small Block Chevrolet with Idler, Big Block Crank Snout COMP Cams Belt Drive Chevy SB W/Idler W