Put a ring of jb weld around the neck if you want a normal civic radiator to match a b18 hose, or use a smaller piece of hose on the neck as an adaptor and slip the larger hose over it. Or use an si radiator, if the neck is the same diameter as the b18, which i would assume is true but not positive.

Don't overtighten the clamp to make it fit. Won't work well, if at all and you might break it.