Header gaskets
Thread Starter
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
Header gaskets
I pulled the headers off the car tonight. I'm going to send them off for coating. Turns out the gaskets have been leaking. Not real bad but its evident on the gasket. They are top of the line Mr Gasket gaskets. Anyone have a better gasket? Maybe something a little thicker to seal better?
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
The trick with header gaskets is keeping the bolts tight. As long as the gasket has pretty good compression on it, it'll do pretty well.
It's not usually that the bolts loosen, but that the gasket compresses. As the header gasket compresses, you have to keep up with the bolt tightness until it is done compressing. If you don't, and the gasket gets loose, the hot jet of exhaust gas going past it will destroy it like a blowtorch.
http://www.chevyhiperformance.com/te...s/viewall.html
Scott
It's not usually that the bolts loosen, but that the gasket compresses. As the header gasket compresses, you have to keep up with the bolt tightness until it is done compressing. If you don't, and the gasket gets loose, the hot jet of exhaust gas going past it will destroy it like a blowtorch.
http://www.chevyhiperformance.com/te...s/viewall.html
Scott
Pro
Joined: Jul 2010
Posts: 691
Likes: 25
From: Boynton Beach Florida
I first used FelPro then tried the Mr. Gasket Ultra and found the same thing. No audible leaks but you could see carbon outside of the seal area so I switched back to FelPro with better results. Just buy the port size and shape that matches the exhaust ports on the cylinder heads.
Melting Slicks
Joined: Aug 2012
Posts: 2,548
Likes: 379
From: Woodinville WA
Percy's gasket.... they're thick (means longer header bolts); but they are reusable and don't leak - even when superdumbguy forgot to tighten one header bolt on used gaskets (couldn't have been me, I'm superbuickguy).... try that with Mr. Gasket 
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Hey, I just bought a pair Percy's reusable aluminum header gaskets. I noticed that they are a laminate of about 4 thinner aluminum gaskets per side. I'll be putiing them on in the spring. I have used Mr Gasket Ultra seal and felpro with much success but they aren't reusable afaik.
Melting Slicks
Joined: Aug 2012
Posts: 2,548
Likes: 379
From: Woodinville WA
Hey, I just bought a pair Percy's reusable aluminum header gaskets. I noticed that they are a laminate of about 4 thinner aluminum gaskets per side. I'll be putiing them on in the spring. I have used Mr Gasket Ultra seal and felpro with much success but they aren't reusable afaik.
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Verdad Gallardo
Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
What I have found that if the flanges are straight and flat and the cylinder head is the same you will not have a leak even with a cheap exhaust gasket.
There is one thing that will get you an exhaust leak even if the above statement is OK. The headers should be bolted up and the rest of the exhaust should be made to fit collector of the header after that.
I haven't had an exhaust leak for 20 years however I just had one because I put on new headers and couldn't find the time to get the Vette to a shop to get the tailpipes lined up perfect. This puts stress on the header bolts where there should be none except to hold the headers to the head.
Once there is an inward or outward stress (pressing or pulling) on the headers sooner or later the bolts will come loose and you blow the gasket. That is why when I was younger I used to blow gaskets because I didn't have the money to instal them as I stated above. So in short you should instal headers from the flange back and don't try and make them fit if they are off a bit, cut the exhaust pipe and weld it so it does not push, pull or move the header in or out
There is one thing that will get you an exhaust leak even if the above statement is OK. The headers should be bolted up and the rest of the exhaust should be made to fit collector of the header after that.
I haven't had an exhaust leak for 20 years however I just had one because I put on new headers and couldn't find the time to get the Vette to a shop to get the tailpipes lined up perfect. This puts stress on the header bolts where there should be none except to hold the headers to the head.
Once there is an inward or outward stress (pressing or pulling) on the headers sooner or later the bolts will come loose and you blow the gasket. That is why when I was younger I used to blow gaskets because I didn't have the money to instal them as I stated above. So in short you should instal headers from the flange back and don't try and make them fit if they are off a bit, cut the exhaust pipe and weld it so it does not push, pull or move the header in or out
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
After years of blowing expensive gaskets I found using regular OEM stock manifold gaskets never blow! If your bolts back out and start leaking the preferared steel gasket can just be retorqued. 
Drifting
Joined: Aug 2010
Posts: 1,839
Likes: 45
From: nassau co. new york
motorhead could this be an argument for flexible connections from the collector flange to the exhaust?i have those cheap ugly pep boy's ones with mechanical clamps but they are very light in weight so that's good.any better ideas for this area.btw i use felpro QMS9275B ultra cheap gaskets and found them the best so far.
Melting Slicks
Joined: Aug 2012
Posts: 2,548
Likes: 379
From: Woodinville WA
motorhead could this be an argument for flexible connections from the collector flange to the exhaust?i have those cheap ugly pep boy's ones with mechanical clamps but they are very light in weight so that's good.any better ideas for this area.btw i use felpro QMS9275B ultra cheap gaskets and found them the best so far.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Never seen one go either
Been using Fel Pro a long time no real complaints
I have to loosen the drivers side to get my oil filter out resnugged them many times no issues. Eventually they will leak like all of them I guess.
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
Stage 8 bolts work and you can use a dremal to ream out the gasket to match your ports.
The collector I usually used no gasket! Just press the flanges together and it may leak a bit on start up but then seals once it gets hot. If it doesn't I've used the aluminum collector gaskets with some luck....
The collector I usually used no gasket! Just press the flanges together and it may leak a bit on start up but then seals once it gets hot. If it doesn't I've used the aluminum collector gaskets with some luck....