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001mustang 05-26-2009 06:48 PM

Straighten bent warped header flange
3 Attachment(s)
What is a good way to true a header flange?

I built up sealing surface by bronze welding then took it down with a long board sander. Are there any other tricks? 05-26-2009 08:21 PM

As long as it works that method is fine. Trouble is brazing really adds a lot of heat, likely worsening the warping problem. Better way would be stick weld w/ 7018 then having the surfaced milled. Stick welding would heat the flange less that the gas welding and of course the mill would be dead-on. Again, if your method worked bolt 'em up and go 6 seconds!

Mike H 05-26-2009 08:40 PM

I have had good luck fixing customers flanges by clamping them to the welding table and heating them up then letting them cool while still clamped. If they are still warped I mig them pretty hot so the weld lays down fast and then grind them flat. I have tried cutting them on the Bridgeport but they are hard to clamp to the mill so they would be safe to cut. I hate throwing parts out of the mill or lathe they usualy hit something painted and not the wall.

cliff tate 05-26-2009 08:45 PM

header flange
draw file each one then cut each flang so they will flexinto place seperatly, brass is ok aslong as there is no leakage, hve brased up many manifolds(cast irone )with good results,headers are a little more forgiving, but if you have not brased them i agree that stick weld with a mild steel rod is better , 7018 is a high tensile rod and only makes fileing more difficult. cliff

001mustang 05-26-2009 11:35 PM

Thanks for the input!

I bolted headers into a spare head and heated a red band around each tube ....not sure how hot to get tubes to relax them.

they are pretty true now.

I am thinking of braze welding a "D" shaped plug in edge of oval ports since my head ports are rectangular and gaskets don't fit that well. I don't expect the header metal to ever exceed bronze melting point (I'm guessing 1700F... I will check it). I am running 351W at less than 365HP. On second thought I will probably tack "D" plug with Mig then fill in with bronze. 05-27-2009 08:07 AM

Cliff; I suggested 7018 'cause I can lay a really pretty bead with it - struggle w/ other rods.

Mike; important safety tip, a header flying free around the room does get pretty exciting!

Another thing you can do is cut the web completely out between the separate tube flanges then each tube can conform to the head separately. That would also put a lot less stress on the whole thing as things heat and cool, expanding and contracting.

001mustang 05-27-2009 10:47 AM

My header does'nt fly around :confused:

My tools walk :nono:

My beads arn't pretty :drunk:

Mike H 05-27-2009 04:11 PM

I built a set of headers for a SBC that the customer wanted to supply his own materials on that the flanges warped on when welding them. (1/4" flanges) I tried to cut them between the outside and center tubes first and they were a pain to get the bolts started on after that. I cut the old flanges off and got a set of 5/16" from Stahl, problem solved.


001mustang 05-27-2009 04:39 PM

cut off flanges
Sounds difficult to cut off old header flanges and weld on new ones.
My headers are very close to block...had to use hammer so they don't touch.

Mike H 05-27-2009 08:15 PM

5 Attachment(s)
It is not to bad I tack the tubes together with a peice of flatbar and cut off the old flange then line uo the new one and tack it check for fit and finish welding it out. Here are a few pictures of the headers I have built this year on customers cars.

001mustang 05-27-2009 08:49 PM

Sweet :drool: 05-28-2009 07:38 AM

Can't think of many things more fun than carving a set of headers! :D

001mustang 06-11-2009 10:15 PM

Thanks all! While reworking the headman 88650 I spoted a used set of JBA 1653 on ebay. Looks like it will now be easy street; fingers crossed. I pinged the JBA to clear steering box.I am ready to blast headers and apply chromex ceramic coating. The JBA has a nice 3/8" flange.:welcome:

001mustang 06-12-2009 10:45 PM

Easy street
3 Attachment(s)
Easy street till I warped the 3/8 flange by fillet welding it. I hope I can fillet weld passenger side without warping it also. I am trying to find best technique to straighten the 3/8" flange.

Possible ways to straighten are:

1. Clamp to welding table and heat flange and tube. Then hope it will be straight when cool. Not sure how much and where to heat it?

2. Someone said I can strategically heat the tube to move flange in right direction. I don't know how but I can experiment.

3. I suppose I can rig a jig and try to straighten in my shop press?

4. Build up the end of the primary tubs with mig welder and draw file straight. I don't have arc welder.

I am not sure of best way?

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