I looked at a collection of spare 1960s Holley? accelerator pump rocker arms (a.k.a. accelerator pump lever) and two R-3259-1s yesterday including a new old stock arm I installed on one of my carburetors yesterday.
The finish is not a crystalline phosphate and oil. It is smooth and hard with just a little gloss. It is extremely thin.
The carburetor in the original post is a post production replacement. Most of the post production replacements made since the late 1970s used applicable small parts from them current product lines. Said another way, parts were used for the job required and not an attempt to reproduce an assembly line carburetor. (The also occasionally had mistakes in calibrated orifice diameters.) The bright accelerator pump rocker arm has the shape of the 1960s part but not the dark finish. The screw and stop nut used in the over travel mechanism are very different than what Holley used in the 1960s. The rocker arm stud was also a later part and that is why the e-clip groove is hidden.
I have some 1960s rocker arms with a faint bronze appearance depending on lighting and view angles. Under my microscope at 20X there is of course red rust where ever the black finish failed for any reason including physical damage. There is and interesting secondary feature. Imagine taking the parts finished in black and mixing them in with something made of copper and rolled around just a little bit. There is what appears, to me, to be a copper or copper colored marking faintly all over on top of the black. I wonder if the black finish contains a copper compound that can create the affect?
