Exhaust gasket leaks

[Adam]

My fresh 440, cast iron heads, and new Hedman Elite headers were leaking, loudly. I first installed them with the gaskets that came with the headers and they didnt cut it. I tried a set of copper gaskets, .050 thick with a .010 raised rib; also didnt work. I could feel the leaks by running my hand close the the flange. I installed a set of Remflex graphite gaskets yesterday and no freakin leaks! They are .125 thick and will crush down up to 50%. They claim they can withstand 3000 degrees. I am pleased so far, but we will see how they last under pressure.. if they don't I will update this post... I was considering going with factory manifolds, but didn't want to give up any power, probably should have. These headers have a 3/8 thick flange and I checked them with a straight edge so I have no idea why they were leaking.

 

[Mopar Mitch]

Hi Adam,

I used to be an aftermarket product engineer with Fel-Pro; worked with them from 1976~2006. The primary reason any such gasket will leak is due to poor clamp load (tap/chase the threadings, plus lube the threadings), out-of-flatness, or imperfect casting finishes (including typical ridges around the ports). The Fel-Pro Performance racing header gaskets should've worked... did you try them? Tubular headers tend to vibrate and lose their clamp loads at the bolts or studs.

 

[moparleo]

Here is one cure for gasket leaks due to fastener coming loose.
http://stage8.com/

 

[Chryco Psycho]

the problem with locking fasteners is often not the fastener loosening but the gasket compressing through numerous heat cycles .
He is also still using the factory studs from the picture ... just saying !!

 

[moparleo]

You are correct that most type of exhaust gaskets normally should go through a couple of hot/cold cycles before they stabilize. These will maintain their tightness upon final torqueing of the fastener.