Just fired my 400 engine after swapping on a set of 96 heads. The IM has a 1972 date code. There is a small gap at the exhaust crossover between the head and the top of the manifold flange. It's small enough I didn't even notice it when assembling, but there's an exhaust leak for sure. Is there a different IM gasket I can use, or some other remedy that someone has employed to fix this problem? I'm sure I've heard this discussed before. I just can't rememember what the fix is. Thanks

You can use a Felpro gasket with the block off, but will eventually burn through. I use/used a thin piece of aluminum or metal for the block off. Metal to metal on the head with the gasket fully surfaced on the intake side.

Thanks Banshee. I was wondering about using a piece of metal to fill in.

Make sure you are thin on the blockoff pieces, yet strong with enough overlap.

I should have some lying around...If I find them, I'll sendthem to you.