Comp Cams roller camshafts are off ered with standard or . 900" base circle and must be used with a bronze distributor gear.Pit Stop USA offers Comp Cams Circle Track Roller Camshaft 292CR-6 - SB Chevy w/ .900 Base Circle - Adv. Dur. 292 Int./308 Exh. - Valve Lift .660" Int./.630" Exh. - Lobe Angle 106 Deg. 12-890-9 at low everyday prices. Be sure to check out all of our products from Comp Cams including Comp Cams Roller Cams - Small Block Chevy.