I'm in the process of port matching the headers for the '57. These are Hedman 1-3/4" round, and the exhaust ports in the heads are 1-3/4" square. I've welded around the primary tubes on the outside and opened up the flange openings to match the port.

In the process, the original weld has been reduced (in some areas, is gone completely on a couple ports). The original width was about 5/16", now at best 1/8-1/4".

I'll have to add material in the areas where it is completely gone, but how much is enough for a seal? Do I need to make it as wide as it was originally?

I'm using Hedman gray paper gaskets. That's what was on before, and they worked/lasted okay.

 

Hehe, I feel wierd giving you advise after you've answered so many of mine and other people's questions... I think this will all depend on what this motor is putting out. I bet you would be safe under most conditions with 1/4"... maybe even as narrow as 3/16", but I really do think you should consider switching to dead-soft copper or aluminum. You can bet on those Hedman gaskets blowing out or leaking badly with the welds being that small.

 

I think the board is messin up, I replied here last night, but it says this thread has 0 replies... Well, just wanted to make sure you got an email about this five7.

 

You ain't kiddin, guess we need to bookmark this page

 

Well, the original gaskets that came with the headers had been on since 1997 (the new ones are the same things). I don't drive it every day since then, of course, but the only place they had any problem was were the flange weld sealing surface didn't extend all the way out to the corner of the port - even there they didn't "blow out", just leaked a little.

I'm still thinking about running a bead around the whole thing and using the Felpro 1.88" square gaskets I have. Just don't like the thought of all that grinding and filing afterwards (filling in the blow-throughs is bad enough ).

As for me asking for advice - hey, read the bottom of my sig (not the "Candy" quote, the one above that).