exhaust leak help!

Are you sure you didnt warp the headers in the process? This will cause you to start off with a minor virtually undetectable leak and allows for the gasket to burn up.

when you change gaskets next, put a straight edge on the exhaust manifold to see if it is warped. If so then get it machined flat or get some headers ( with a thick steel flange 5/8" ). When you assemble it again snug all of the bolts down, then torque the bolts from the middle towards the ends. That way the manifold doesn't get warped. ALSO. After you drive it a couple of times, retorque the manifold bolts AGAIN. The gaskets compress a little after a few heat cycles, allowing exhaust gas to leak out, which will eventually burn through to gasket. You might also want to look into locking exhaust bolts, which have a little allen head in the center of the bolt to keep the bolt tight. They work for me, although I think they were about 80 bucks from summit racing.

I hear nothing but rave reviews about Ford gaskets. They are around 25/30 bucks, and Mustang guys swear by them. Just get some spray on "Copper Thermal barrier", and forget about them.

I used to have this problem with a 200CI 6-cyl in my '65 (back before it grew two more cylinders). I had Clifford headers on it, and the header gasket between the third and fourth cylinder used to blow out consistently, leaving my otherwise mellow-OK sounding 6-cyl sounding like a thrashed Vanagon with a blown-out head gasket. I'm sure you can relate.

Mr. Gasket makes (or used to make) header gaskets for this engine. They're the 'fiber' type, without a metallic core. Summit has some made by Hooker under their P/N HOK-10827HKR that appear to be similar.

Order that gasket, and soak it overnight in a tub of water. Don't use your wife's turkey pan. Trust me on this. In the morning, disassemble the headers and clean them and the cylinder head. Check your header flange, as noted above, to make sure it's not really, really warped (if it is, this isn't going to work, and neither is anything else). Make sure the rest of the engine is ready to run. Take your dripping header gasket and install it. Bolt up your headers just like normal, but don't dawdle here - you want them to remain wet. Tighten your header bolts and start the engine. Let the engine run for long enough to evaporate all of the moisture from the gasket - at least 20 minutes or so. Voila! Exhaust leak solved. The wet gaskets will conform to whatever imperfection was causing your leak in the first place (which is still there, by the way!)

This was the only thing that worked for me on the 6-cyl after trying dozens of combinations of gaskets, sealers, etc. The wet-the-gasket trick then sealed the exhaust up for the next dozen years (until I got tired of 120bhp). Hope that helps

Are you sure that you cleaned off all the old gasket that might have been left behind before putting the new one on? I have seen where folks had thought they blew out a chunk in the past only to find it fused to the manifold instead and left an uneven surface behind.

Personally I think all the cardboard gaskets are crap, even the copper backed ones, they just do not hold up and will need replacing always. I do not know if they make these for your 6, but I decided to buy really good gaskets for my 8 a long time ago and I haven't had to replace them once no matter how many times I remove my headers, the name says it all and worth every penny. I had a constantly recurring exhaust leak for 3 years before these bad boys.

http://www.percyshp.com/seal-4-good_header_gaskets.html