Is this too warped to use?

[ajmcforester]

I'd take some of the warp out and get a crush gasket if they make them for the z that will make a tight seal.

[5thhorsemann]

I'd take some of the warp out and get a crush gasket if they make them for the z that will make a tight seal.

the nismo gasket is a crush type.

[kcc0234]

I had a horribly warped L6 header (about 3/8" end to end) straightened by a local machine shop with very good results, and only a $40 bill. They used a large press to take away the majority of the curvature, then ground the flange to ensure it was flat. If you go this route, just make sure the final ground height of the flange matches your intake! Otherwise, you'll have trouble getting a good seal using the factory intake / exhaust washers.

[Z train]

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.

Same type(flange wise) that is on my turbo car.Since there is a bolt on each side of each tube(sans the 3& 4 tube)Cutting the flange will have no ill effects.And since header makers do INDEED make flanges of this type,it is not desperation but rather another design that has been in existance for 45+ years.

Now if you want to discuss the right way to do it,that involves stripping, straightening and re-coating.

[ajmcforester]

If you can I'd consider sending them back, but I would call the manufacture first. They might take care of you.

[5thhorsemann]

Same type(flange wise) that is on my turbo car.Since there is a bolt on each side of each tube(sans the 3& 4 tube)Cutting the flange will have no ill effects.And since header makers do INDEED make flanges of this type,it is not desperation but rather another design that has been in existance for 45+ years.

Now if you want to discuss the right way to do it,that involves stripping, straightening and re-coating.

Isn't the exhaust isolated, weight-wise, on a turbo car? We can argue this point endlessy, my point is that if you remove part of the structure,the integrity of that structure is compromized. Cutting the header up is a fools bet. if you are going for one race, thats one thing. If you are trying to put a header on a street car, or a daily driver, you are asking for trouble by cutting up the header flange. It's bad advice, and a stupid way to fix a problem that was created by the welder that bent the metal while fusing the parts in the first place. I'd like to see you take a Saws-all to a $300 part to solve a 1/4 inch fitement issue.

I'm not looking to throw you under a bus, just saying that this is not the sort of problem that requires a torch and saw.

[FastWoman]

You can probably straighten the thing in a very controlled manner by bolting it down (on the ends) to the narrow side of a wooden beam (e.g. 2x6) that you've radiused with a hand planer. You can start out with a very mild radius, bolt it down, remove, measure, steepen the radius, bolt down, remove, measure, etc. When you've JUST started to bend the thing, you've just gone into strain. At that point, you can figure out how much farther you need to bend it (e.g. 3/16" more on the ends), steepen the radius by that same amount (e.g. another 3/16" shaved off the end), bolt it down, and you should be done. (It might be good to bend it close to the mark first, and then make the final adjustment in another pass.) If it doesn't flatten out satisfactorily, then maybe the machine shop can mill it flat. However, you won't have lost anything. That's approximately what the machine shop would do (except perhaps without wood) before milling the flange. You can probably even return it in the re-bent shape, as your bends couldn't be any worse than the manufacturer's, and I doubt they would even notice.

[motorman7]

Lots of advice here. The one I like best is having the machine shop straighten it for $40 bucks. That would be well worth the money spent.

I say that based on experience with my MSA 6 into 1 headers on my '71. Nice pipes, but the number 5 tube had a small 1/16"-1/8" gap when checked for straightness. I put in an extra gasket to span the gap and installed the headers. After a few weeks, the gasket blew through and I had a small exhaust leak. Time to take it apart again.

I ended up welding a bead around the number 5 tube flange and filing it till it was flush with the other tubes. This has worked well without blowing through.

I think you have to make this interface flush before you install. I would not count on the bolts to straighten the flange. Might work with aluminum, not with steel.

Just my thoughts.

Rich

[Gary in NJ]

There have been many good suggestions for straightening the flange but I wouldn't attempt any of them without heat applied to the surface.

My suggestion is send 'em back for a unit with a straight flange. You paid your money, get what you paid for.

[ajmcforester]

There have been many good suggestions for straightening the flange but I wouldn't attempt any of them without heat applied to the surface.

My suggestion is send 'em back for a unit with a straight flange. You paid your money, get what you paid for.

agree otherwise you will leave micro cracks in the metal

[Zed Head]

Did you buy them new so you can get a replacement or did you buy second-hand? If second-hand and you have to make it work, the easiest, first thing to do might be to clamp the flange to a flat surface and get an idea of how much force it will take to flatten out the sealing surface, and see if it flattens or just bends in a new place.

I would guess that the hardness/stiffness of the flange might be affected by whether or not the manufacturer quenched or annealed the welds, and how hot they got when welding. I'm just guessing, I am no expert.

Also, there's nothing wrong with telling the brand so that future header buyers can be aware of, or avoid the problem. I might have headers in my future and wouldn't mind knowing where these came from.

[steve91tt]

Did you buy them new so you can get a replacement or did you buy second-hand? If second-hand and you have to make it work, the easiest, first thing to do might be to clamp the flange to a flat surface and get an idea of how much force it will take to flatten out the sealing surface, and see if it flattens or just bends in a new place.

I would guess that the hardness/stiffness of the flange might be affected by whether or not the manufacturer quenched or annealed the welds, and how hot they got when welding. I'm just guessing, I am no expert.

Also, there's nothing wrong with telling the brand so that future header buyers can be aware of, or avoid the problem. I might have headers in my future and wouldn't mind knowing where these came from.

I bolted them to the head without a gasket to check how much torque it took to flatten them out. I was impressed to see that the flange could be straightened so that it sat flush with the ports with much less than 8 foot pounds. Given this result I went ahead and installed them with the supplied paper gasket and some high temp RTV. I put about 50 miles on them last night and no leaks so far. I'll re-tourque the nuts tonight and let the forum know if leaks occur with time.

These are Pacesetter headers sold by Rebello.