Originally posted by Dirty
Since they match up so close, why not cut the flange off the 4g63 manifold and weld it on the 420a manifold. Then just port the 420a flange. Thats what I'd do. If you make an adapter plate, I wouldn't drill out the holes for the 4g manifold. I'd weld in some studs. I think it would be a ploblem to get the manifold tight enough to the 420a flange to make a seal. Then you have to get the whole damn thing on the head. It just looks like you might have to skip some bolts to get it on, but maybe not. If you cut the gasket around the bolt holes, you could see a little better what you have to work with.

4g manis are cast iron, gl welding that