About two years ago, I bought a bunch of parts to build a 1967 firebird. Some of the parts I bought as a package deal. The car is almost completed. The engine is completed. I have a set of 670 heads left over that was part of the "package deal". A few of the valves almost look like theres a crack from the outside of the valve straight to the center. Does anyone know what could cause this and are the heads possibly damaged? Brent
