I had a set of swap meet headers on my 56 3200 with a 69 327 but I could not seem to get the headers to not leak at the heads no matter what gasket I used. I went and bought a set of Summit brand 9606 for it and they are the same. The only thing different on this 327 is it has a set of those later model EFI heads, the ones you have to modify the center intake bolts. I am almost ready to swap the headers for manifolds. I was thinking my last ditch effort would be to get a pair of those copper gaskets, does any have any experience with them working better? It seems to be louder on the drivers side, I have tried different header bolts, they are as tight as heck, square gasket, round gaskets, nothing seems to help. I can't see or feel any gaps anywhere and it's driving me crazier than I already am.
Unless you have headers with 3/8" flanges chances are that they are going to leak. I have used permatex silicone with the copper in it with good success to stop header leaks @ the head. Its called Permatex Ultra Copper and you will need to glue both sides of the gasket. Let it skin and first and don't over tighten it.
The vortec style heads have higher exhaust ports than the traditional small blocks.. Almost what is known as a d-port exhaust.. Generic small tube headers won't seal. Posted using the Full Custom H.A.M.B. App!
As stated above the thickness of the flange makes a huge difference. I now running a set of Sanderson headers that require no gasket and I sealed them with Permatex Ultra Black and have had no leak issues since in I installed them three years and many miles ago.
Have you looked into the Remflex gaskets? They are amazing. I have been using them on the headers for my daily driver GMC truck and with about 50000kms, They have never leaked, I even had to remove the drivers side header once and reused the gasket and still no leaks. I have conviced my friends with leaking headers on there rods to try them and no one has had a leak since. They are fantastic. http://catalog.remflex.com/
Take some rubber fuel hose about 3 foot long...hold one end to your ear and use the other end to search for the leak while it is running. Run the loose end around the potential leak spots. When you find the leak you will know it and be better armed better in how to fix it. It may sound like it's one place when it is someplace else.
Pull the headers and you will be able to see where the leak is. If they are leaking at the ports run a file on the header flange to check for high spots. File them flat. You can try the copper but I have had the best luck with the silver or grey metal gaskets with silicone ultra on both sides. Dont over tighten the bolts.
Thanks for the replies, I am going to look into the gaskets mentioned, it does appear to be leaking only or mostly on the drivers side at the top of the ports.
One other consideration; are the bolts just a bit too long and bottoming out before they are truly "tight". Butvch/56sedandelivery.
If you look closely at the old header gasket you can see where it is leaking. I've had problems with the ground down weld surface area on the flange not matching the head port surface area and it blows out the gasket in "thin" spots as a result. To remedy this I've built up the weld in the deficient areas on the flange and ground/filed it down to match the pre-existing flange weld. This provided the additional sealing surface to finally stop the leaks. Not saying this is your problem but it's definitely something to check out .
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