I attempted to install Holley 890005B valve covers on 1969 440 big block with stock heads and stock HP exhaust manifolds. Because of the shape of the HP exhaust manifold on the passenger side, these Holley valve covers hit the exhaust manifold and will not install. By my research, if you have a B-Body or C-Body with 440 and HP exhaust manifolds, 1967-1971, these valve covers will not install. Reason: the wall of the valve covers extend completely over the mounting surface so the Holley 890005B valve covers are wider than stock and hit the passenger side HP exhaust manifold, which rises above the valve cover mounting surface and curves slightly toward the valve cover mounting area. Pics show difference between Holley and stock install.