Short version, my 92 track car has a wonky cat converter. It's rattling and until I realized what it was making that noise it had me very worried. Years ago I bought these Phab headers on eBay for a couple hundred bucks and never installed them. Reason 1 was that they were simply not the right hook.ups.for my car, they use EGR.ports from the L98, and frankly I think they're L98 headers in general. Reason 2 was they used 3 bolt connections instead of slip fitting onto my factory exhaust. So both of those things needed welded up, and it never was a priority. Well, now it's on the table and instead of paying someone who knows what they're doing to do it, we're gonna do it ourselves because as Jeremy Clarkson says, "Well how hard can that be?"

I ordered a welder, gloves, and a mask. I ordered a dual.exhaust.pipe kit, x pipe, 3 bolt flanges, and basically have what I think I'm gonna need to pull this off. Here's what we are starting with.




Step 1 is getting the EGR stuff off the headers because it ain't right for the car. I considered just capping it off, but that seemed like more of a pain than it's worth. A hacksaw was taking too long, so I got impatient and grabbed a big *** pair of bolt cutters I had. That worked like a champ and made quick work of those pipes, though not exactly flush. I will end up coming back in here with an angle grinder or something and cutting them off flush before I weld them (though frankly, welding these tubes shut would probably be easier and have no issues).


So we're gonna give this a shot and see how it goes. I have never welded before, except for one time a.buddy showed me.how to do it to remove a very stripped bolt, but I have the power of all of humanity's co.bined knowledge at my fingertips and watched some YouTube on it, so I think I'll be fine. Gonna need to get these old manifolds out so that I can get the headers in. I don't THINK I'm gonna wrap the headers right now that may be a really critical mistake, since I'd like to remove that heat from the engine bay, not radiate it off the headers into the engine bay. The headers themselves seem pretty decent, they're equal length design so that's nice. If I'm gonna nitpick (and I am) the collector doesn't seem as well designed as others I've seen, there's no come inside it and the 2.5" outlet is a little small vs the size of the primaries, but whatever, we aren't going for max gains, we're going for "taking off the broken cat converter".

I may add some high flow cats to the system. I haven't really decided yet. The C4 is a lot shorter of a vehicle than the catless trucks I've been around, and so it could be noticeably more stinky as a result. That could get real annoying sitting on grid for an autocross or hpde real fast. I probably should do that and header wrap. Oh well, we'll see.

 

Did a little more "prep" work tonight. Research says I have two O2 sensors (that are likely gonna be a pain in the ***), and the headers only have a provision for one. So my options were drill and weld in a new O2 bung on one of the header collectors, or do something else.

I was already thinking about adding cats, because I was worried about the stank. Cats usually come with O2 bungs welded in already. So that made it a pretty easy decision, so we will have cats, and I will likely weld the cats to the 3 fla.ges, so they're the immediate first thing from the headers, with the O2 bungs in the front. I don't think high flow cats are directional so should be OK. As a bonus, the cats even came with O2 bung plugs, so I can send back the one i bought.

 

If you are going to dive this far into it why not cut off the three bolt flanges from the collectors and go V-bands? They are 1 million times better. and yes they can be MIG welded on.

 

Well now that's an idea. Honestly, I hadn't even considered it. Guess I'm gonna need to do some research.

I'm gonna be flux core welding, so not the best option, but I think it'll be fine.

EDIT: OK, we are changing direction and going V Bands. Good tip!

 

Doing exhaust with flux core is doable. Just messy.

I'm no expert exhaust welder that is for sure, but I have hacked a **** ton of exhaust together with MIG. Even a lot of stainless steel stuff. Building homemade exhausts is definitely a hobby of mine.

Looking forward to seeing how this project turns out on your C4.

I'm in the process of building a new mid pipe and axle back on my C5 using full 3 inch C6 exhaust all the way out the back. It is coming along nicely.

Got V bands at the collectors and the axleback so I can just drop the whole mid pipe out at will.

 

Here is a good video specific to welding exhaust tubing with flux core.

 

Got a bit more work done tonight including the most exciting part,my first welds! They're not pretty, but they don't leak any light, so I guess mission accomplished sorta.

We ended up here, haven't really die grindered them down to look nice, and frankly was just trying to figure out what in the hell I was doing. Will grind them mostly flush and then if I have to redo them some.


This is the other side, pretty much where we're started before welding. Ground the holes down to be basically flush.


I found what worked best for me was sticking the wire down in the hole and making swirlies lol. Proper technique? I have no idea. But it got metal where there was once air so I guess that's something.

I also ordered the v bands. They're definitely nicer kit. I haven't figured out how I'm going to cut the flanges off. I started with a hacksaw, and boy that's gonna be a hell of a lot of work, but I can at least follow the flange for it to be fairly straight of a cut. Professionals would probably have a chop saw or band saw or something like that. I don't, lol. It's gonna be a hacksaw or a sawzall, and frankly I don't think the sawzall is gonna give me a very straight cut.

The v bands came in today too. Frankly, if the v bands weren't so much nicer looking than the 3 bolt flanges I would be giving very real thought to skipping them, but damn, these cheap v bolts were SO much nicer in materials than the 3 bolt flanges, I can't bring myself to not use them.

 

Go to harbor freight and get yourself a 39 dollar angle grinder and some thin cutoff discs. It is one of the better ways to cut off exhaust tubing during fabrication. Sometimes even better than a chop saw.

I like to use 2 inch masking tape to make cut lines with when I can. Especially for V bands as it helps keep the cut square.

Yep, the worst part of flux core is it is MESSY.

 

Took your advice and used cutoff wheels to take off the flanges. It worked pretty damn well. My welding is still not great, but I have v bands on and EGR holes plugged and I don't think I'm gonna have any leaks (based on my highly scientific test of "stick a bright *** led inspection light in it and look for light").


This is how my first flange cutoff came out. Not super straight trying to follow the flange, but definitely workable. Would have probably come out nicer if I remembered that tip about using painters tape as a guide but here we are lol. After this shot I took the grinder to it a bit more to level the end out.


This was the second side after plugging the EGR ports. Is it pretty? Not really, but it's solid and better than the first one lol.


Here's the v band on, before cleaning the welds. After grinding them down it was still quite not pretty, but I think it was probably sealed. I went around the inside with another bead (which honestly was easier to do, I dunno why, but it felt like I could see better and was getting my pace better, getting a nicer weld inside)


Here's the little el cheapo welder from Amazon. As you can see, I'm using the best of the best for everything, including my work space, as I'm doing it in my driveway (because I pulled all the plugs and wires on the car in the garage so it's not like I can even back the car out lol).


Oh, here's something interesting that I hope isn't foreshadowing, the headers and collectors actually are slightly canted inward. I hadn't noticed it before, but the collectors are point slightly towards the center of the car. Weird, but oh well.

So half of my v band is welded on. I was about ready to weld the other side onto my cats and then I had an epiphany... Don't do that yet, make sure they're gonna fit where the headers land, they're bigger than pipe. So I didn't weld the other side of the v bands on. I THINK they're gonna fit fine... But better to test for once the headers are on.

The manifolds are currently soaking somewhat in liquid wrench. Hopefully that helps get these things off without breaking the bolts.

 

Good to see someone else teach themselves welding for the first time. Its also good to see someone show their work, takes guts sometimes. At 61 yrs old i just finished my first welding project. I made and welded in a plate for a crossmember gusset on my ‘01 Silverado. Needed to do it for State inspection. Heres the result. This was thicker material obviously so im sure welding thinner exhaust tubing is more tricky to get satisfactory. I havnt welded any exhaust tubing yet but I can imagine doing it eventually. The welder I bought was the cheapest Harbor Freight flux 125.

 

Fauee, is that a DC out welder that you bought? Most of them can change output polarity. For flux core, you want the ground clamp to be positive (+) and the wire in the gun to be negative (-). If the polarity is not set optimize flux core, it will still work but with more messy results.

 

Maybe? I think it said it was a DC inverter welder.

They called it multi function, and it does have multiple connections to change polarity. I set it up according to the picture for flux core mig, which I think was clamp positive. Stick welding it said to do that opposite I believe. It also can do "lift tig", but I don't have gas so that's a moot point to me. I'm not entirely sure why you'd use stick welding when you have flux mig honestly, but it does it.

 

I was going to buy the HF welder, but the return policy on the Amazon one was better (in case I gave up on this whole idea). I suspect they're pretty similar spec wise though, as this one is also 125A.

Welding has been on my "learn how to do" list for a long time. I bought these headers in probably 2017 and I wanted to learn it since then, but finally decided to make it happen and I'm glad I did. What's the point of having all the accumulated knowledge of humanity in your hands if you don't use it to learn new things, right?

 

You can double check your polarity with a voltmeter. Some of the instructions can me wrong.

The lowest level HF welder that I bought is actually a flux core dedicated machine. It was the only welder I could readily get that was spec to run on my 20 amp circuit. It has AC output so I can’t change the polarity. AC current alternates polarity 60 times a second. So, the HF flux 125 is just going to be on the more messy side.

Are you welding with the plastic tip still on the end? I saw a tip on YouTube where the guy recommended just removing the tip for flux core. Makes it much easier to see the work as you weld. It was helpful to me. The plastic tip is really only needed for MIG as its purpose is to keep the gas directed at the end of the wire.

If you haven’t tried it yet, remove the plastic tip and trim your wire to about 3/8” exposed before starting to weld. I definitely find it much easier to see what is happening.

 

Got the full exhaust off today, including the manifolds. Now I'm to the part of the install where I'm like "are these even gonna fit?". Being that they're those Phab headers, that's a definite possibility that the answer is no, lol. Right now it seems like the driver side one is too wide, which I can help with some "persuasion" with a hammer on the tubes.... But they might fit with some lifting of the motor. Gonna unbolt the engine mounts and lift the motor a little and see if that gives me the extra room needed.

I coated these headers with eat woods internal ceramic coating, neat system, I used it on my Trailblazer SS headers as well. Downside of it was it found a leak in one of my primaries where I tried to seal the old EGR ports. So I'm gonna have to fill that hole with the welder before I get them all bolted in, but not a big deal.

 

Interested in more details about what you used for the ceramic coating inside the header, and how it was applied, cured, etc.

There's a saying about welding that grinding and paint makes a weld look great.

Stainless exhaust can be easily tig welded, and it's one of the most satisfying things to weld I think. But you have to practice and get the settings right, and with a tank of Argon for purge and the torch. The biggest advance I've made in stainless welding was installing a set of 2.0 cheaters under the shield so that I can see it all magnified, as the trick is to keep the small sharp point very close to the puddle without touching. Burns Headers has a lot of good tips on welding 18 gauge (0.045") stainless, they should know of course. Only 35 DC amps max needed (well within a 110V AC outlet capacity) and you can use stainless mig wire for a filler rod. With out the purge it is very weak and prone to cracking.

Reinstalling my custom home made exhaust as we speak, had to remove it to change out the rear spring to a VB&P one.

 

I used this

https://www.eastwood.com/eastwood-hi...on-nozzle.html

This is the second time I've used it, and honestly I did a lot less prep than last time. The first.time I rinsed the inside of my headers out with acetone I think they sell (or sold) a cleaning spray that was basically acetone too. This time I just let it rip. Basically it comes with a long *** straw, with an end on the hose that sprays out of 4 corners. You basically stick it down the tube, and then spray while you pull it out. It sprays a lot of material out, so you don't have to worry about it too much really, it coats everything it reaches. You're "supposed to" cure I by heating and baking it. But uh, it's inside the primaries, so once it dries, it's not going anywhere. So I just thet the exhaust heat cure it.

I've had it on my TBSS headers for years and it definitely helps keep some of the heat inside the headers. Is it as good as a full cerakote or similar coating? I dunno. Is it as effective as header wrap? Again, I have no idea, probably not? But for ~$35 shipped (I bought mine on Amazon because it was cheaper with shipping than buying direct from Eastwood, to figure), it definitely does make a difference.

 

Lots of work done today. Previously got the manifolds and exhaust out, so next step was to put the headers in. How hard can that be right? Well, I have Phab headers as a reminder, which don't exactly have the best reputation...


And frankly, that's probably not deserved. They slid in basically fine from the bottom with the proper perspective. I did loosen the engine mounts to the lift the motor, but only had to do that for the passenger side. Driver side slid right in once getting the car lifted high as hell. Pics for proof! Also note how decidedly ok my welds look after some paint, thanks for hiding my lack of skill paint!



The hardest part (and where I lost motivation for the night) is getting them bolted in. I have them "in" but getting them actually properly lined up and torqued in is definitely a pain in the *** (not made any easier by these things BARELY fitting in width wise - I was genuinely convinced they were too wide for a bit today full disclosure. They have an equal length design and so they are WAY wider than something like the Hooker or Hedman or EM or TPIS or any of those "not quite equal length" headers.)

I do think they'll fit, but they're not gonna make it easy. Also, the primaries are kinda huge, and so bolt access sucks to be blunt. I was planning to use ARP 12 point bolts, but frankly, I think that's not gonna happen, I simply cannot get a socket on them in a lot of cases. I have a set of the socket cap style bolts where you use an Allen key coming, these are way more of a pain to get torqued in to the proper torque rating, but I think the smaller tool size to tighten them is going to be more beneficial here, and they will just get torqued to the German spec of "gut an tight".

Other notes, I think the accessory support bracket will need notched, which means the ac compressor bracket likely will too, it seems like the flange hits the primary. I had planned to use a longer bolt and a spacer here, but I'm not sure if that's going to work now. Possibly another socket cap screw will work.

On the underside of the car, I haven't started mapping out the exhaust, but looking at where it lands plus the size of the cats I bought... It looks like it's gonna be tight to get the cat and the 45 degree bend in the space behind the collector. I could potentially make the turn first and then put the cats a little further back, but my o2 sensors are going in the cats, so it puts them fairly far away then. I have no idea if that matters at all. The other option is to just trim the cats down as best I can, and maybe trim some of the 45 down so it doesn't take up as much space. Once I get the headers actually bolted in and the obligatory open headers start up video, I'll start worrying about making it legit. Oh, and PCM of NC said that adding long tubes and deleting air and EGR I should retune my car, so I have that to do too.

I tell you what, this has been a lot of work to clear up a rattling catalytic converter, lol.

 

Blue Demon makes a flux core stainless welding wire for flux only machines. You'll need to reverse polarity though. I did this with my Harbor Freight Titanium 125. I had to crack open the welder and just swap the leads on the main board. It wasn't hard. Just understand that you need much higher voltage to weld with stainless wire. So you will be running that welder on a very high setting just to weld exhaust. It did a great job for me when I welded new slip on collectors for my LS swap.

I gotta commend you on learning to weld to get your project done. I lost count of how many times I see guys here who won't try a project because they're too scared to buy a cheap welder and give it a shot. Good for you for learning. Now that I've been welding for years I look back at some of my early lumpy *** welds on my car that are still holding up and I just smile.

 

A bit more progress. I have decided that for the Phab headers (I suspect many others are similar here), the ARP bolts are NOT the way to go. The small 12 point head makes getting them started by hand while trying to hold the header in place and inventing new swear words wishing you had 8 arms like an octopus a lot harder. The socket head screws on the other hand have a nice finger sized head, with ribs for your pleasure and easier grip. They're also like half the cost, which is nice.

The alternator support brack is gonna be easy peasy to put in place. Honestly, I don't remember how it came out but putting it in, it's gonna fit like it was supposed to go on headers and not manifolds. I must have it flipped but it lines up great, gonna get a slightly longer bolt for here and send it. I think the dipstick will be the same way currently, probably won't even bother with a longer bolt here. The AC compressor bracket I think will need.a spacer, no big deal, and a longer bolt.

So slow but steady forward progress.