Factory Header Material

[TurboWh1]

Does anybody know what grade of material was used to build the factory headers? I think it is a stainless of some sort. But I know its not 304. Is it maybe 409? I'm going to be doing some welding and want to ensure I use the correct wire.

 

[JDSfastGN]

its a cheaper grade for sure, 409 I believe....

 

[Bruce Urie]

I agree with you.....it's the 409 grade, not the 304.

Bruce '87 Grand National

 

[turbofabricator]

Standard ER70S wire works fine in a MIG. It is considered weldable stainless. It can even be gas welded with a carborizing flame. BUT.....no matter what process you use, it WILL crack again. Just a matter of when, not if.

 

[Heg87t]

Does anybody know what grade of material was used to build the factory headers? I think it is a stainless of some sort. But I know its not 304. Is it maybe 409? I'm going to be doing some welding and want to ensure I use the correct wire.

Check it with a magnet. 409 the magnet will stick, 304 it will not.

 

[TurboWh1]

Check it with a magnet. 409 the magnet will stick, 304 it will not.

Yes a magnet sticks to it. I was hoping to weld it. But then again its been fixed once before. However its not a good weld job.

 

[BIGPSI]

Standard ER70S wire works fine in a MIG. It is considered weldable stainless. It can even be gas welded with a carborizing flame. BUT.....no matter what process you use, it WILL crack again. Just a matter of when, not if.

not exactly true. been 10yrs and still no cracks on a old pair of Dwight headers

 

[boostedturbotom]

Race gas does wonders on stock headers !

 

[bison]

Bead blast the area to be welded and TIG with inconel rod.

 

[TurboWh1]

Bead blast the area to be welded and TIG with inconel rod.

I was hoping to save the header. Its actually already been bead blasted. The crack is the usual 1" long in the typical place. It appears to have been welded previously. I guess I could buy a stock replacement header but I really didn't want to fork out the cash on a new header at the moment. I have a mig welder in the garage but I would consider having somebody professionally tig weld if it would hold up.

 

[Chuck Leeper]

Gas purge the tube when you do it....

 

[jhanson1750]

The stock 86-87 headers are 410 grade Stainless. I have scanned a couple of sets with a PMI and they all come back as 410. Yes the best weld repair is done with Inco you just have to watch the post weld heat to keep the weld from cracking. Using a backing gas or not has shown no impact on the thin wall tubing of the headers. The biggest factor we have found in keeping the headers from recracking is post weld stress relieving in an oven at 1200 degrees for 1 hour and control cool over the next 4-6 hours. Just what I have done and works well. Jon Hanson

 

[Heg87t]

Hm...

The stock 86-87 headers are 410 grade Stainless. I have scanned a couple of sets with a PMI and they all come back as 410. Yes the best weld repair is done with Inco you just have to watch the post weld heat to keep the weld from cracking. Using a backing gas or not has shown no impact on the thin wall tubing of the headers. The biggest factor we have found in keeping the headers from recracking is post weld stress relieving in an oven at 1200 degrees for 1 hour and control cool over the next 4-6 hours. Just what I have done and works well. Jon Hanson

Interesting. Do you heat the headers before welding or just after? When you say controlled cool do you slowly cool them back to ambient?

 

[BobbyBuick]

Get ahold of Steve Hughes.I think Dwight is living in the area now .He did my GN headers in 97 and still perfect.I think Steve knows how to do them and last

 

[Chuck Leeper]

The reason I suggested back purge was to prevent/reduce creation of "sugar slag".. Not something I'd want to run thru a turbo...

 

[bison]

When you say controlled cool do you slowly cool them back to ambient?

Bury them in sand

 

[Bruce Urie]

A suggestion for you: Send them for welding to Scot W. at GNS Performance.....he says he knows how to to a crackerjack job, and also welds a brace on the headers.....he said not ONE he has ever welded has come back...

Now THAT'S a strong statement, and Scot has more than proven his worth....so,if you want them done right, send them to Scot. He cares about what you want done.

Bruce '87 Grand National

 

[TurboWh1]

Thanks for all of the great ideas guys!!!!!! I'm ready to get the engine back into my car and the cracked header is holding me up...

 

[jhanson1750]

Yes controlled cooling is allowing the metal to slowly come down to ambient.
The backing gas will help if the welding is burned in too hot. We pre-heat with a rosebud but just to get the surface moisture out. I have made a 1" plate to bolt the headers flange to before it goes into the oven to keep the distortion down. Then check and surface if neccessary. I will post some pics.
If you are looking to have yours fixed and Scott from GNS has a good track record then that would be the way to go. The ones I have done are for local guys and very little time pressure so I could do them at work. Good luck with them. Jon Hanson