My stock exhaust manifold is warped and leaking badly so I decided to upgrade to a header. The one I bought seems to have a warped flange. With a straight edge the deflection end to end is about 1/4"

This is my first time installing a header. I know that some of the flange warpage can be taken up when torquing to the head but is 1/4" too much? Should I send it back?

Thanks for the help.

My stock exhaust manifold is warped and leaking badly so I decided to upgrade to a header. The one I bought seems to have a warped flange. With a straight edge the deflection end to end is about 1/4"

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This is my first time installing a header. I know that some of the flange warpage can be taken up when torquing to the head but is 1/4" too much? Should I send it back?

Thanks for the help.

I'm not 100% positive but I do believe that headers come with a warped flange which straightens out when you bolt them to the manifold.

Jan

I'd contact the manufacturer first, see what they have to say. I bought a used header on ebay and it had a warped head plate. I flattened it out on a steel table by clamping it down with shims under the high spots so it could over bend a bit. Just took my time and worked it slowly. After I bolted it on it sealed up nicely without a problem, be sure to work from the center out when torquing it down, and don't overtighten or you can damage the aluminum head.

I suppose you are way too far down the road to discuss how that cast iron manifold may have gotten "warped".

Just beware of overpulling steel studs in aluminum heads trying to flatten our a header flange.

Push comes to shove,cut the flange between 1&2 and 5 &6.One thing i don't like is i can't see any "build up" around the tube to seal against teh gasket.No mater what you're gonna need some "Ultra Copper" to seal things right.

Thanks for the advice guys.

Bruce, the cast iron manifold came to me warped. It's so out of wack the holes do not even line up. I took the head to a machine shop and it checked out as flat and true. Just the manifold out of wack.

Push comes to shove,cut the flange between 1&2 and 5 &6.One thing i don't like is i can't see any "build up" around the tube to seal against teh gasket.No mater what you're gonna need some "Ultra Copper" to seal things right.

My header was flat like this one, no ridge like on a V8 header. I used a NISMO gasket without any sealents and it sealed up fine, I wouldnt cut that header, you will end up replacing gaskets all the time as the header will work it's way loose as the motor rocks around in the mounts. just straiten the flange.

I just put the non coated header 6 into 1 on my sons and it came the same way. I was not happy but it sealed up fine. I just went over the bolts several times.

Those studs in there will pull that down with no effort.

, I wouldnt cut that header, you will end up replacing gaskets all the time as the header will work it's way loose as the motor rocks around in the mounts.

Sorry,but there is no correlation between cut flanges and them working loose.

Sorry,but there is no correlation between cut flanges and them working loose.

That is a 6 into 2 header, the flange keeps the 2 peices honest. Since there are no stud penetrations through the flange you will lose the shared torque of all the sprung washers and effectively create a smaller amount of resistance to support the weight of the exhause system. Seems to me that this will cause the gasket to fail. I have never liked the design of the intake/exhaust manifold mounting on these cars, not a fan of having to pull the intake for an exhaust leak and vise versa. Cutting up a new header in stead of straitening it is a bad idea, desperation in stead of inginuity.

I'd try to work the bend out like 5thhorseman said, personally.

Like others have said, I've seen the wimpy aluminum threads get pulled right out before (thanks PO). My head has a few helicoils now thanks to someone putting too much torque on the studs. Keep in mind that the studs are spec'd for a low amount of torque (maybe 12 ft-lbs IIRC?), and that may not be enough to force the entire flange down against the curve from end-to-end.