Early '66 HiPo Alternator Finish

[OldGuy]

Guys, I remember a discussion(s) about the factory finish that was on the black HiPo alternator pulleys. I remember that the correct finish is not black paint of any type but was something like PO or black zinc that was oiled for protection. Can anyone provide me with the proper finish data? A picture(s) would also be helpful if you have some available. I am restoring an original, non-plated pulley.

Thanks in advance for your help.

Frank

[Bob Gaines]

Guys, I remember a discussion(s) about the factory finish that was on the black HiPo alternator pulleys. I remember that the correct finish is not black paint of any type but was something like PO or black zinc that was oiled for protection. Can anyone provide me with the proper finish data? A picture(s) would also be helpful if you have some available. I am restoring an original, non-plated pulley.

Thanks in advance for your help.

Frank

My opinion is that it is the Black Chromate. This is based on the fact that I have had a few that still had the chromate finish in part on the back side of the pulley where it was sealed by the fan blade from the elements and you could still distinguish the rainbow iridescent effect common to black and gold chromate parts.When put in perspective the progression from a black chromate to the more common seen gold chromate also seems to be a logical conclusion . FYI chromate goes over a already zinc plated surface. With that said it was common to use the additional chromate  corrosion protection for electrical parts on 65-70 Shelby/Mustangs as the assemblyine manuals confirm.I am set up to do this process PM me if you are interested .

[J_Speegle]

Not certain of the finish - guess it would be a good idea to find a way to test an original to find out for sure. Don't see the blackish finishes where they deteriorate back to a plain zinc finish as we see on aged as exposed dichromate (gold finish). Black chromate IMHO is likely a good current choice at this point without testing or documentation on an original engineering drawing of the part

Service replacements may have been painted to protect them from rust while they sat on the shelf like many other parts were

Here is a picture of original pulleys so plenty of wear and age showing. Not easy to get nice clear pictures on the car. Uppers are the earlier - lower the later versions

[Bob Gaines]

 For those looking for a pulley alternative I double checked on a repro hipo pulley that I got from NPD within the few months for a display engine and it is the stright engineering number style vs the curved and it is done in black chromate instead of black oxide or paint.

[OldGuy]

Bob and Jeff, thank you for your replies and your collective wisdom.

Frank