56 Holly Carburetor Manual, Model number 4000. This manual covers disasssembly, cleaning, rebuilding, and adjustment information, 16 pages and illustrations. This is a supplement to the 55 Holley Carburetor Manual, LIT3A, and it covers only the points of difference between the two versions of this carburetor. 55 models the choke mounts on the manifold, 56 the choke is on the carburetor body.