The Stovebolt Site Forums The Shop Area Engine Shop William's, a Fenton knockoff and a poor product.

I do not know if the difference in flange thicknesses is a new thing, because I did not use Fenton headers on 216/235/261 engines "back in the day".

The Fentons that I bought in 1997 had a flange thickness that did not match the dual-carb Offenhauser intake. I had to grind the flanges on the Fentons to match the Offenhauser flanges.

The Fenton headers' flanges do match the thickness of the Fenton dual-carb intake manifold (as it should). And, the Fenton headers' flanges almost match the thickness of the original 235/261 intake manifolds (I am using original clamps but they are at a slight angle).