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Discussion Starter · #1 ·
What the heck am I missing? The drivers side has no problems with the gasket that came with the headers but the pass side is leaking like crazy.

Upgraded to 1/8" compressed ceremic header gasket and still the same. I've tightened the stage 8 header bolts so far I'm afraid I'll twist their little heads off! They are the short ones so not bottoming out.

Is there something special about the pass side with these headers I need to do? I'll drop $40 on those pillow like gaskets if I have to but I want to be sure they'll work. Anyone had this problem with this combo before?

Thanks

Dave
 

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Make sure the flange is not obstructed. You may need to grind clearance to ensure the header flange seats properly. If that is not the issue, check with a straight edge to see if the header flange is perfectly flat. Any warping can cause the same issue.
 

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FFCobra Master Craftsman
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Check that the mounting surfaces are flat. Put a straight edge on the header flange. I had the same problem, flanges were true, couldn't find the source of the leak. I switched to Percy's gaskets and all is good.
Doug
 

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Is it the P heads that have the diffrent exhaust ports from the normal gt40 heads? If this is the case, do you have the correct headers?
 

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Discussion Starter · #5 ·
These ARE the "P" heads but the headers are advertised as design to fit (they are Ford Racing M-9430-P51).

I guess I'll take them off again to check to make sure they're true and try the other gaskets.
 

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I have the FFR/Hooker headers and GT40P heads. The bottom inside edge of the header flange hits the head where there is a bump, kind of between the lower head bolts. I have one side worse than the other. I ground a bevel perhaps 1/8" wide on the inside edge of the flange.

Sounds like you have a different model header but the problem could be the same one. Get underneath with a bright light while everything is assembled and see if you can see the header flange hitting the head.

HTH,

Chris.
 

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my passenger side FFR header also leaked despite several different gaskets. Turned out, it was warped, sent back to FFR for replacement, and all good after.
 

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I have same set up and had to grind off top of motor mount to get clearance, they would not seal till i did, hope that helps
 
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