New 1967 GTO exhaust manifold casting
I just received a new exhaust manifold for my 1967 Pontiac motor, 462 CI, and there is a gap in the casting (straight part between center d-ports (separator?)), right at the face where it attaches to the head. It is only about 1/8" wide, but it is deep (about 1/4" from the face of the manifold). I was told by the manufacturer that it should not be a problem, but I can't resolve the fact in my mind that it was put there for a purpose (keep cylinders separated) and there will be blow by between them right at the manifold connection to the head. This may be a problem, but I am not getting the feeling from the manufacturer that they are worried about it.
Anyone else have this issue, or better yet, is this a problem?