Header Qs

[Matt Weiser]

What is the proper welding rod/wire to use when welding the stock headers? I know it's stainless but isn't it a particular variety?

Also, should any gasket material/sealer be used when installing the headers?

Thx...

 

[tim87tr]

I had read on the gaskets that people use the Felpro 1400. I could not seem to find these and bought some other Felpro pn#. I ended up just cleaning the header and exhaust with some sandpaper and thinner. Used a thin film of orange high temp around the header exhausts and let it dry firm in about an hour, then reinstalled. Used antisieze on header bolts and torqued to 30 ft-lbs. Service manual said 25 and read here 35.

As for the welding, the machine shop that just did mine used stainless, but not sure what type. They had to make 3 passes to get the stainless weld to take since the crack was bad. I emailed a board member about a triangular gusset to use on the DS header between 3 and 5(he had web pics), and had that done. His weld/gusset is on its 5th year. I had a spare junk head that they bolted the header to when welding. They put it in something to cool down slow for 3 hours.

 

[Matt Weiser]

Thanks for the reply. My problem is this. I purchased a set of used stock headers that had already had the "infamous" crack repaired and it looks like it was done well. Unfortunately, I discovered a hairline crack where the #5 header tube meets the flange at the cylinder head. It appears to be very small, but it's obviously a leaker because I can see soot outside the header at that point. I don't have a spare head to bolt it to while getting it welded. Should I worry about this little crack? Is it possible that it leaks only when cold then closes up when the engine's hot? Damn. :-(

Any advice appreciated...

 

[TDS-84]

From what I've read, DON"T WELD THE HEADER WITHOUT BEING BOLTED TO A HEAD! It would probably warp, and you'd never get it to seal up afterwards.

Heck, I'd bet you can go to a slavage yard and get an old head for super-cheap. Would certainly be worth it, IMO.

I suppose that the leak could change once things are up to temp.
I don't know how much difference it makes, but I have heard a lot about not being able to make the boost with even small leaks.

 

[tom h]

A leak is a leak ... it's not going to get better or go away on its own.

I believe the stock headers are 409 stainless, a relatively crummy grade of ferritic stainless (unlike the high quality austenitic 300 series).

More info on stainless grades at http://www.atlas-steels.com.au/techinfo/index.html

309 filler rod is recommended by Atlas due to its greater ductility, which should lead to less cracking.

I recently had small 1/8" NPT ports welded onto every tube of my headers (for inserting thermocouples), but it's going to be a long time before I know how dureable it's going to be. And, a small round port is probably not subject to the same stresses as a tube/flange connection.

 

[Matt Weiser]

If I can't come up with a spare head to bolt this header to while welding, what about just bolting/clamping it to a known flat surface instead? Better than nothing or just a feel-good move?

 

[UNGN]

Originally posted by Matt Weiser
If I can't come up with a spare head to bolt this header to while welding, what about just bolting/clamping it to a known flat surface instead? Better than nothing or just a feel-good move?

Better than nothing, but a head is by far the best. The header that cam with my car has the #5 pipe 1/4" out of plane with #1 and #3. I'm guessing it was welded without bolting it to a head.

I just did one using TIG that had a MONSTER crack that almost went from the crossover flange up and over and back to the crossover flange. Bolted to the head it was still flat after welding.

 

[Matt Weiser]

Sounds a lot like the original header I took off my motor. A real ugly POS that was fixed wrong. It actually looks like someone tried to fix it with some kid of high-temp epoxy, then used a grinder or something to smooth it out. The #5 tube was nearly cracked clean off and had gaps almost big enough to swallow a pencil.

 

[Chris McDade]

I just welded the outside of my headers without having them bolted to anything.. Not Recommened...I had them welded with 309 rod weld. I worked really nice. I then ported the headers and cleaned them up some. After I had them welded and did the port work to them I gave them to my machinest and had him do a fresh cut on the flange. The headers came out real nice. I don't have them on the car yet..I will let you know if they have leaks.

Good Luck