bowed/warped header flange

[rossman]

One problem with removing that much material is that now the flange is thinner in the middle. This is only a problem where the washers overlap both the intake and exhaust. I may have to notch the washers where they overlap the intake so that tightening the nuts clamps down on both equally.

[zxtman]

One problem with removing that much material is that now the flange is thinner in the middle. This is only a problem where the washers overlap both the intake and exhaust. I may have to notch the washers where they overlap the intake so that tightening the nuts clamps down on both equally.

 

If you could have a portion of the washers milled to remove the appropriate thickness, that would work.

Or, you could use shim washers (of the appropriate thickness) cut in half and tack welded to the exhaust flange: this way you could use the factory washers as is.

[rossman]

Yep that would work too. I actually like that idea better. Another option is to remove material from the intake. I noticed the washers are cupped. I'm guessing this was done to accommodate slightly different thickness flanges.

 

If you could have a portion of the washers milled to remove the appropriate thickness, that would work.

Or, you could use shim washers (of the appropriate thickness) cut in half and tack welded to the exhaust flange: this way you could use the factory washers as is.

[Tony D]

If it warped before, truing it will only let it warp again later.

JeffP went through this with his SFP Tubular Header. We stress relieved it and imparted 0.100" counter stress while heating to put a 'reverse strain' into the metal at the relaxed state. After a couple of hours on the dyno, we ended up pulling things apart, and it was already starting to warp.

 

There is a stress in the piping that is pulling that flange. Putting in flexible bellows in the appropriate long sections of the tubing, to minimize the tubing expansion stresses imparted to the flange. That is the source of the warpage, not the welding on the flange and tubing joint.

 

Now that the flange is a different thickness, this likely will reutrn in short order, and unfortunately be worse.

 

Good Luck!

[m4xwellmurd3r]

I have a question then tony

 

If you have a header that is warped, and a spare head to try and true it, would it be fine to run (ie:seal properly) as long as you heated it to true it if you took it off and it warped again?

 

I guess my question is

 

Can you indefinitely true a warped header flange?

[saiko]

We had this problem on cast iron manifolds on an SBC once. All we did was get long studs and slowly threaded the manifold on until it was straight and flush. After it was against the head, we swapped the studs out for proper bolts and called it a day.

 

A friend of mine used to race circle track and he said they would do this all the time. The heat just expands the metal and causes it to warp when removed because there is nothing holding it straight.

 

good luck

[rossman]

If it warped before, truing it will only let it warp again later.

JeffP went through this with his SFP Tubular Header. We stress relieved it and imparted 0.100" counter stress while heating to put a 'reverse strain' into the metal at the relaxed state. After a couple of hours on the dyno, we ended up pulling things apart, and it was already starting to warp.

 

There is a stress in the piping that is pulling that flange. Putting in flexible bellows in the appropriate long sections of the tubing, to minimize the tubing expansion stresses imparted to the flange. That is the source of the warpage, not the welding on the flange and tubing joint.

 

Now that the flange is a different thickness, this likely will reutrn in short order, and unfortunately be worse.

 

Good Luck!

 

That's interesting Tony. If tubing expansion causes the header to warp then I would expect it to warp the other way around. The outer pipes, 1 & 6 will expand more than 2 & 5 and 3 & 4 so I would expect the outer ends to be pushed inwards, towards the head. I think what is happening here is that the end of the flange is being pulled out away from the head. It seems like tube contraction is causing the header to warp. Could it be then when the header gets hot that is expands and stress relieves itself and then when it cools it wants to pull the flange back? That might explain why it would continuously warp. I dunno I'm not materials expert.

[rossman]

Is this the kind of bellows you are referring to?

 

http://www.treadstoneperformance.com/product.phtml?p=371&prodname=Stainless+Steel+Flex+Couplers%2C+Bellows+with+Interlocking+Lining

[Tony D]

The bellows are similar. Mercedes 280SEL has a nice example on their manifold from what Jeff tells me.

 

They pull away from the head at the ends 1/6 just like yours is doing. Same as the SFP tubular header. There is a lot of metal to expand and put a stress on it, and the longer a straight run you have, the more expansion in a given plane you will have. Add to that they are outside the 'bundle' of the tubes in the center, so they cool faster than the center (follow where this is heading?) so the expansion is the most on the longer straight runs, where that expansion can push harder against whatever it's pushing against. Then when shut down, the center stays hot because all the close mass, while the outer two cool faster, and pull back. Make sense?

[rossman]

Make sense?

 

Yes it does.

 

I'm looking into some bellows. The pipe ODs measure 1.66" which I believe corresponds to 1.25" pipe. Of course I can't find anyone online with bellows that size. Anybody know of a source?