The coating on the main parts and castings are considered sacrificial. In other words they give up their molecules over many years of exposure to the atmosphere instead of the parts they are protecting rusting, oxidizing, pitting out, etc.
Once those coatings are gone, like the zinc that covers the metal parts, rust sets in quickly. Bead blasting or anything that "etches" the main casting and airhorn will allow the base material direct exposure to fuel on the inside and everything else on the outside.
This new fuel is pretty hard on some metal parts. It delaminates the newer Holley castings, especially the brightly polished looking Street Avenger series. I've had enough of them sent here pitted out on the inside to know that it happens.
The jury is out on how well the Quadrajet casting hold up done in similar fashion. I don't put them out there that way so don't get any direct feedback from that deal.......
