Mods- if you feel the fabrication board is a better place for this, feel free to move it.

I'm in the process of making my second set of headers for my 3500 Fiero swap, and thought I might share a few tips I've learned from the making of the first set.

1. FITMENT FITMENT FITMENT! Pipe fiment is everything! if you want clean good looking headers inside and out, make sure the pipes fit perfect before you start welding. this means the primary tubes fit where you need them, and that there is no gap when you but them together where they will be welded. if they don't fit perfect, they are not ready to be welded!
   
2. find a comfortable place to work. don't work sitting on concrete where you cant be upright and have full range of movement, it makes a big difference in the finished product!
   
3. Check your machine before every weld!
   IE: on my welder, the power switch is right next to one of the heat switches, if I'm not paying the utmost attention, I may inadvertently switch to high heat from low and start blowing holes instead of welding.
   
4. tack tack tack, then weld.
   on each seam, start with for tack welds, do one at 12 o'clock, then 6, then 9, then 3, if you do one big seam, the pipe will warp and cause fitment issues. also don't weld the whole seam until you're sure it's where you want it, it's much easier to cut a few tacks than a whole seam.
   
5. Invest in a high quality welder that uses a shielding gas, or tack the pipes with your welder, and have a friend or welding shop do the final welding. the welds lay down much smoother, and will seal better than with flux cored wire. Of coarse this mainly applies to those of us who don't have a TIG or are not Oxy Acetylene welding our headers.
   
6. Invest in a tubing cutter or any other tool that can cut the full width of your pipe in one pass.
   it's much easier two weld to strait cuts than two crooked cuts, I picked up a pipe cutter for $20 at Lowe's (plumbing section) that will cut most header primaries no problem. funny, sounds like tip number 1 doesn't it?
   
   Edit: I recently found a chopsaw (for wood) on craigslist for $20, I bought it and an abrasive wheel that fits it and found that it makes a very good cut on the pipe, with minimal burs to deal with, it also leaves nice square edges that are easier to weld.
   
7. weld the flanges and colectors LAST.
   it's easier to weld up the full length of your primaries when they aren't bunched together.
   
8. Last but certainly not least, PRACTICE PRACTICE PRACTICE. order enough materials so you can practice on the same size and thickness pipe, it will help you get a feel for your welder, and the materials you are working with.

When I was done welding my primaries, I built a pressure tester that I could hook up to my air compressor to test my welds, it cost less than $20 to make, and has worked great so far,

I made it out of an 1 1/4" PVC repair coupling, a 2" PVC cap, a air line coupling, some epoxy, and a rubber expansion plug.

drill a 5/8" hole in the 2" cap, and epoxy the air line coupling in, the epoxy the 2" cap to the repair coupling.



The repair coupling's threaded ring and washer will fit over a 1 5/8" primary that has been pressed into a "D" shape, and then you can tighten the coupling and it will seal against the outside of the pipe, the seal may not be perfect, but it doesn't have to be.

then get the rubber expansion plug, and tighten it into the other end of the primary you want to test.



now hook an airline up to the air coupling you epoxied to the cap, and apply pressure, I would not go past 25-30 PSI, you don't need to, and I don't trust the epoxy to that.

Brush a mixture of your favorite dishsoap and water over the welds and look for bubbles, if you see bubbles, you have leaks!!!



Some of the guys on the Fiero forum had a little to add.


The following only applies to Stainless Steel:

you have to be careful if you do the following and are not an experienced weldor, it makes it much easier to blow holes in the pipe, and create restrictions in the pipe.