I have a 263 straight eight in my 37 Buick and it cracked two exhaust manifolds which are getting hard to find. A friend that ran a small block Chrysler in his circle track car which isn't an engine that every FLAPS carries header gaskets for clued me in on red high temp silicone. I then used neither alignment rings or gaskets which I figured might let the manifold "creep" between hot and cold. That was twenty years ago and still holding with no leaks--exhaust or vacuum. The manifold and head MUST be surgically clean before applying sealant.

[img]https://i.postimg.cc/Rq34bd8V/Pont-heater-Buick-sealant-003.jpg[/img]


Evan