I am redoing the exhaust manifolds on my '94 F350 7.5L since it had a leak and a broken bolt (pass rear of course). I can't decide whether to use an SCE embossed copper gasket or a Fel-Pro laminate composite gasket. I did have to mill the manifolds flat again since they were warped about .020" taller in the middle than at the ends. I know they came with no gasket from the factory, but I don't trust it will just seal up now.

Thoughts?

 

Copper, with some of that red high temp silicone.

 

 

I have no experience with exhaust gaskets, I do have 3 460 engines that need exhaust manifold gaskets. From my readings in the different forums people have had best luck with copper gaskets. Their are those who don't use gaskets and use Copper RTV and have had success with sealing exhaust manifolds and headers that way. When I do my exhaust(s) I plan on using copper.

 

 

I've used soft copper on three engines (headers) now and if you'll take the time to get them fully compressed they will seal till hell freezes over. And the bolts will not work loose.