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.
That will be a problem down the road. On the dyno when using aluminum heads and headers, I do use copper exhaust gaskets but those do have a tendency to leak. With the exhaust manifolds being machined flat at the head mounting surface, then a thin film of RTV should suffice.