buffer (bÅ­f'Ér) Chemistry A substance that prevents change in the acidity of a solution when an acid or base is added to the solution or when the solution is diluted.
These Ford Racing Performance Head Gaskets are specifically designed for use with cast iron or aluminum cylinder heads on a Ford 289, 302, 5.0L, or 351 Windsor V8 engine.
FYI, I use iron heads with FPT copper header gaskets and FPT headers and have had good success. I also use studs (actually set screws with allen heads) and nuts. I think this evens out the torque load on all things involved. An added bonus is an easier installation and removal of the header.