Hedman Header Gaskets

[Deano2002]

I believe it was the year before last that I installed my Hedman Ceramic coated headers. The gaskets that came with were what I thought were normal but, with less than a thousand miles one is shot already. I did tighten them up like instructed but the drivers side failed already (junk). I bought some Remflex gasket which are Graphite impregnated and much thicker, hope they hold up.

 

[lynnmor]

Headers usually are not flat and the pressure on the gasket is uneven.  After a large number of heating/cooling cycles the header will become stress relieved and then the the surface can be fly cut.  After that the gasket may last. 

 

[touchracing]

Back in my hot rod days my go to was to get 2 sets of the thick paper Mr. Gasket header gaskets.  I'd soak them in water overnight then install them nice and tight.  Then go for a little drive to warm everything up.  After a the motor cools down retighten the header bolts and you are good to go.

 

[Deano2002]

Headers usually are not flat and the pressure on the gasket is uneven.  After a large number of heating/cooling cycles the header will become stress relieved and then the the surface can be fly cut.  After that the gasket may last.

shouldn't have to cut them for what they cost, I expect to get a sealing header out of the box. haha, well these are nice thick gaskets, it is sealing now but I will carry a torque wrench along

 

[Deano2002]

Back in my hot rod days my go to was to get 2 sets of the thick paper Mr. Gasket header gaskets.  I'd soak them in water overnight then install them nice and tight.  Then go for a little drive to warm everything up.  After a the motor cools down retighten the header bolts and you are good to go.

I did read about someone saying this a couple years ago. anyone familiar with the Remflex gaskets?

 

[catblaster]

  I have always cut the header flange between every two cylinders, allows the tubes and flanges to expand and contract. Solid copper gaskets I have heard are the best. My Cummins 8.3 insists that composition gaskets should NOT be used in instead of the stamped metal gaskets so the manifold can move and expand.

 

[kdbgoat]

Like Will, after fighting exhaust leaks, I also cut between flanges. I always had nothing but problems with the thick gaskets, but had no problems with Fel-Pro header gaskets. They are very similar looking to stock exhaust gaskets.

 

[sightseers]

I had a 454 Chevy that constantly cracked the exhaust manifolds, broke the mounting bolts and blew out gaskets.

I finally put on a set of Doug Thorley headers on it that had 3/8" thick (split) flanges. they had these great split copper composite gaskets.

That was the end of all my exhaust problems.

 

[catblaster]

I had a 454 Chevy that constantly cracked the exhaust manifolds, broke the mounting bolts and blew out gaskets.

I finally put on a set of Doug Thorley headers on it that had 3/8" thick (split) flanges. they had these great split copper composite gaskets.

That was the end of all my exhaust problems.

After fighting that on my 8.3 cummins I finally cut it up into three pieces and oversized the holes. Clamped them back together with SS bands and header wrap tape. No problems since.

Take this same problem with heat cycles causing expansion and contraction and you can see why a "seasoned" engine block is preferred for a rebuild. When a block is blueprinted back to factory many of them will have shifts in cylinder bores, decking will not be parallel to crank or crank journals not straight.

 

[Old_Crow]

I had a 454 Chevy that constantly cracked the exhaust manifolds, broke the mounting bolts and blew out gaskets.

I finally put on a set of Doug Thorley headers on it that had 3/8" thick (split) flanges. they had these great split copper composite gaskets.

That was the end of all my exhaust problems.

Back in my motor home tech days I must have worked on hundreds of 454 exhaust manifolds.  That's where I learned about cobalt drill bits and those Snap-on screw extractor kits that work so well. 
GM's final fix was a different formula for the material used in casting the manifolds, cut the flange between all cylinders, use brushable anti-seize on the surface where the manifold bolts to the block, and anti-seize on the manifold to block bolts.  Never any gaskets of any kind.  At one point we were taking the old, warped manifolds, having the flanges trued and then cutting the flanges between the runners and installing with anti-seize.  That seemed to work pretty good on the coaches that were out of warranty and the owners didn't want to spring for new manifolds.
This was in Cali, with the cast iron manifolds.  I don't  believe I ever saw any of the stainless steel, 49 state manifolds leak, but then I was in Cali at the time, and didn't see a whole bunch of the SS ones.  I'd probably true and cut the flanges on them too, if the occasion arose.

 

[sightseers]

20 years ago on that 454 was where I first saw a guy mig weld a 1/2" nut on to my 3 broken off studs and easily un-thread them..

I've been using that method to remove broken bolts ever since.

 

[namumac1]

If I remember correctly Fel Pro had a gasket you could use with headers, and they worked!

 

[Old_Crow]

20 years ago on that 454 was where I first saw a guy mig weld a 1/2" nut on to my 3 broken off studs and easily un-thread them..

I've been using that method to remove broken bolts ever since.

I've used that since those days, but back then I didn't know how to weld.  I got to be real good at drilling out the center of the bolts and then removing the remaining threads with a tap. 

 

[sightseers]

I used to drill them, and tap clean them too....and then once my Snap-On tool guy watched me doing a broken stud removal at my shop and he handed me a reverse direction drill bit broken stud removal set.... and told me to try this !...

I was amazed !..  as soon as the bit started to really cut,  90% of the time the stud would unscrew itself.

 

[Old_Crow]

I tried those reverse bits too.  They work okay in some situations, but the bolts they use to bolt the manifolds to the heads have some strange threads(don't seem to be fully cut until you use them), and with the extreme heat in this application they just seem to weld themselves into the head.
One thing I learned early on...do not, repeat, do not break a drill bit or easy out off in the head.  Changing a head on a BBC is no fun if you do it with the engine still in the coach.

 

[sightseers]

my friend just went through that on a 7.3 Ford diesel,  he lost his patience trying to remove it and broke a drill bit,  ended up taking both heads off to start with new gaskets.

(side note)...one of the best penetrating oil's I've ever used is a 50/50 mixture of ATF and acetone.