header leak ???wtf

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71scamp78

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ok I got some 440 with some hooked super comp headers and the damn things are leaking between the two exhaust valves on the 440..I took them loose put a new felpro ultra seal gasket on twice and it blew them out as soon as it started . The is clean and dry flat so im sure it's the header surface . I cleaned it best I could no luck and the headers are in good condition..What's the best next step to take it gets expensive to keep blowing it out and I can't stand the sound of a Leakey header gasket. Should I try and double up the gaskets or buy a new set of....????
 
Have you put a straight edge on the header flanges?
 
B/RB are notorious for bowing the center 3/5 header flange if they are overtightened. youll need to get the flange back to straight and torque to spec. Let the gasket do the sealing. I think the Super Comps still use that phony "O-ring" scam so your a little less prone to bending that flange but anyone can wrench that down and bow it.
 
I don't wanna take the header out..it's in a 69 gtx 440 I just bought it's a real pain to take it out..I'm just wondering if I should try a copper or aluminium gasket maybe or no
 
If the header flanges are not straight, there ain't a gasket in the world that will keep it from leakin.
 
Amen, Rusty.
GOTTA be flat/straight to seal. If you can get it out and press it back flat, you can sometimes run a belt sander lightly across those o-ring welded parts and get yourself a good fitting header.
 
You could try to double up as a last effort. But if that doesn't work ultimately you will have to yank the headers. Sorry man.
 
Have You Put
A Straight Edge On The Header Flanges ?

You come to us for help and then don't answer questions. That's not how to get help.
 
I had this issue when I ran headers. I picked up copper gaskets. They wont burn out and should conform to any "bends " in the flanges.
 
Rusty is dead nuts, if it ain't flat you're pretty much doing temporary bandaids.
Remove header. Weld bead on flange to bring up to level. Grind flat. Install (with any gasket you want).
 
well I pulled the header and the welds around the tubes looked bad between the two exhaust valves. I took a sander to them knocked off a bunch of loose metal and some of the pitting . One question I have is should I sand the welds completely flat or will that cause it to blow a hole through where tube and flange is welded. I bought a set of Remflex gaskets supposed to be good.
 
No don't grind it away, that bead is what provides the seal. The flanges on headers with less than a 1/2" thick flange should be beaded like that. Plus they'll crack if you grind it all away.
 
ok that's what i figured..I just sanded with a sanding wheel to smooth it out. It looks much better should seal with these new gaskets
 
Last edited:
71scamp78 said:
ok that's what u figured..I just sanded with a sanding wheel to smooth it out. It looks much better should seal with these new gaskets
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Remflex sealed up my Hedmans (without any touch ups) , I bet you'll be ok. Just go easy, don't over-tighten.
 
Is this a common flange header? If it is, you NEED to use a straight edge across ALL of the tubes. Repairing only the center tubes will not give you the answer. If the outside tubes are not level with the inside pair, and especially if they are higher and you smooth out the center two, then you will actually make the problem worse, because you will make the center tubes even lower yet. I recommended the straight edge not for you to ignore me, but so that you will GET IT RIGHT.

Use a straight edge across ALL FOUR TUBES so you will KNOW instead of guessing.


OR continue on blindly and possibly make things worse.

Seriously, do you want to pull the header YET AGAIN?

That is it for me. This is getting so damn old.
 
Well good. IMO that's a necessary step for header installation that most people just leave off. Glad you did it. That really tells the story, doesn't it?
 
If you get it flat, you WILL have success!
 
skizzo said:
No don't grind it away, that bead is what provides the seal. The flanges on headers with less than a 1/2" thick flange should be beaded like that. Plus they'll crack if you grind it all away.
Click to expand...

I wouldnt take that as rule, many headers are flat flanged. I prefer the flat ones as the shape of the "O-ring" is not accurate to the shape of the port. If you hog the ports out, you exceed the dimensions of the "O-ring" especially on the SBM motor with its unique port shape. The flat ones have about 5X the sealing surface, and you are not concentrating the exchange of heat from the headers back to the heads via a 1/8 bead of metal, but a very large full face flange. IT all boils down to a smooth face, flange or O-ring.
 
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