This is how I coated my exhaust manifold on my MGB. I had it media blasted clean and checked all the gasket surfaces for flatness. I masked them off then used sprayed VHT ceramic coating on the inside and out waiting for it to dry to touch. I then took my charcoal BBQ and got it up to 500 degrees F and baked the manifold off for 30 minutes (which is enough for VHT) to set the coating. POR 15 is great stuff as well. 3 years in and it still looks new and by coating the inside as well makes it flow better and keep cooler. P.S. Look into Remflex for gaskets, they NEVER leak.

Very nice job...thanks...🔧🔧👍

Looks great I need a oven in the garage

I think .004" should work. I resurfaced the exhaust manifolds for my 64 galaxie on a big belt sander and the closest I could get the centers from the outers was .002" and it's sealed up just fine now going on 3 years. I'd say tighten the center bolts first to suck the center in a bit, that's what I did. The coating looks nice.