[Rachelsdad]

When I first switched my '63 Bonneville (389) back to duals (stainless) in '86, I had a real Dickens of a time getting the pipes and the flanges to line up squarely.

More recently, the engine was rebuilt and everything put back together (not by me). I have a noticeable leak on (I think) the passenger side, and it sounds like it's right up front. The likeliest culprit is the flange. What is everyone using these days for good sealing? Extra thick gaskets? Brands?

TIA

[tom s]

If it’s head to manifold use Remflex

[Rachelsdad]

Interesting. Thanks. Completely new to me. Just found their website, and have been reading up. ;-)

[ZeGermanHam]

Yes, Remflex gaskets are 100% the way to go for the manifold flange against the cylinder head. They're thick and compress to form a very good seal. They have to be handled a little delicately during installation, though. Don't want to bend them.

[Rachelsdad]

Quick follow-up to all of this:

As it turns out, the leak was coming from the mating surface of the exhaust manifold. A couple passes on the surface grinder and voilà! No more exhaust leak.

The '63 really wasn't meant to use flange gaskets, apparently. The output port is rounded, and the pipe should just be drawn tight to it (assuming it is smooth enough to make a proper seal, and of course, a stainless exhaust pipe is going to be tough to get "form fitted" to the manifold).

Anyway, all's well that ends well. No substitute for truly flat mating surfaces.

Thanks for the Remflex pointer, though, guys. I've got their site bookmarked for future reference.