slightly warped 304ss exhaust pipe flange

[3046moparcoupe]

Submitting this post under the old mindset saying of "an once of prevention is worth a pound of cure" Almost wishing I would never have persured the idea of getting a 304 ss exhaust system on this old car, but I have too much skin in the game now to not continue onward with the effort. 

 

I spent quite a while researching the area for someone who tig welded, and who could answered the questions I had learned to ask in regards to trying to get this flange welded on to the exhaust pipe correctly. What type of filler wire do you use for 304 stainless ? answer : 308, what type of gas ? answer ; Argon,....etc....finally found a fella that did a lot of TIG welding, he also had a small machine shop, and I was impressed (gut feeling) with the guy in all aspects of how he carried and conducted himself....

 

Picked the piece up, beautiful weld,...and I know without a doubt the fella wen tout of his way to do the absolute best for me he could. reason I say that, is I had taken him a 304 stainless flange I had purchased from Summit racing, which had slotted bolt holes in it. We had discussed cutting the oval slots out of the flange, in the shape of a round plug, and making 2ea round inserts that would fir into the cutouts. These inserts would be drilled with the round 7/16" hole and would serve to keep the exhaust pipe centered at the manifold. once he started the process, he realized that it would be less work and a far better end result to just make an entire new flange out of 304 stainless (3/8" thick just like the one I brought him), position and drill the holes and weld the flange on....and that what he did...

 

Got underneath the car yesterday and the bolt holes are a snug fit, but the 2ea 7/16" bolts did both fit through the exhaust manifold holes and through the exhaust pipe flange holes. pulled te pipe back off, and another close look at the flange had me walk over to my bench and grab a straight edge,...during the process of welding, the flange warped some....when laying a flat edge on the gasket surface, out on each far end of the flange I see about a 32nd" of gap, which of course slowly diminishes on both sides as you move inwards towards the center. According to the flat edge, almost all of the warp is from the mounting holes outward,....my only thought was to work with flat files to true this surface up again....as I realize that gasket material could take up some of this, but I also feel I gotta have even surface pressure for the gasket to last, and most importantly to not end up cracking the mounting ears on my cast iron manifold.

 

I've filed for about 4-5 hours now, and it's incredible slow,...course that's OK, I don't much care how long it takes to end up with the proper result...however I got to thinking and wondering today, if their might be a better way,...I don't know that I'd trust anyone to mill it, as I haven't had much good luck with machinest so far in this area...I('m just wondering if it could be straightened out with heat, or some other process,..?? I'm just removing material, which might be OK,...might make this flange weaker down the line in regards to future possible warpage from heating and cooling down....?? a possible question for you forum members out there with more experience than I...again , this flange is 3/8" thick (which is a bit thicker than the old rusted flange on my old exhaust that came off the car (which looks to measure around 5/16 " thick)….if I continue to file on this, I will have to remove a little over a 32nd of material across the face of the flange to get it square.

 

I'm doing my best to cross hatch when I file, even circular motions, and always holding the file with the palm of my hand, and holding and pressing the file up against the flange in the very center of the flange,....in effort of trying to get it as true flat as possible. Certainly something wide enough to cover the entire flange on every pass would be better....??

 

All thoughts and input greatly appreciated.

 

thank you again

 

Steve

[Young Ed]

you need a giant sander/grinder to do the whole thing at once. 

[Plymouthy Adams]

chuck that sucker up in a vice...get a nice large flat mill bastard file and proceed to work it level.....be quick and easy and the only way shy of a milling action that will assure a degree of being flat....

[DJ194950]

Your welder most likely has one of these  to make quick work of your flange.

 

Well the whole page comes up on my posted HF. What I tried to post is the large disc sander on that page  like that I used to do exhaust flanges that warped for old Mopar flat motors at work many years ago.

 

DJ

 

 

Search results for 'disc sanders'.html

Edited December 14, 2018 by DJ194950

[kencombs]

32 minutes ago, DJ194950 said:

Your welder most likely has one of these  to make quick work of your flange.

 

Well the whole page comes up on my posted HF. What I tried to post is the large disc sander on that page  like that I used to do exhaust flanges that warped for old Mopar flat motors at work many years ago.

 

DJ

 

 

Search results for 'disc sanders'.html

That, or a large 6" wide stationary belt sander will work also.  Even though, IMO the 1/32" would be easily handled by the gasket.

[Dodgeb4ya]

The pipe should stick out and above the flange approximtely 3/8" to 1/2" to be like the factory header pipe...helps prevent leakage and less pressure and heat on the gasket.

The manifold has a slightly enlarged bore for this.

File away ... carefully.

 

Edited December 15, 2018 by Dodgeb4ya

[plymjim]

  Guess you're already past the 3/8 to 1/2 extension mentioned by Dodgeb4ya.

That being said, you now have a pretty flat surface to work on. I've been lucky

so far with a Craftsman hand held belt sander for similar tasks. our local

hardware sells emery cloth belts for it from very fine to coarse. Cuts pretty

fast whatever grit you use though so be careful if you go this way. Good luck. 

[PatrickG]

Search for "exhaust collector donut gasket"
With that style gasket you will have no issues with the warped flange.

[Plymouthy Adams]

the doughnut needs an inner metal liner and should have ball flanges on the both sides when nutted in place...this unit should have a liner and standard exhaust flange gasket with the metal squish ring...

[Dodgeb4ya]

I'd re- do the flange...

[PatrickG]

*duplicate post 

Edited December 17, 2018 by PatrickG

[3046moparcoupe]

DB4YA, I originally had enough vertical length on this pipe (before the flange was welded on) to have it insert up into the exhaust manifold just like the old rusted steel exhaust system that came off it, however I was bothered about Galvanic Corrosion eating away at the inside of my cast iron manifold if I did that...…so I began trying to figure a way to connect this up and protect my cast  iron manifold.

 

At one point - I did what I'm obviously really good at, and posted the question here on the forum, many folks said they wouldn't worry about corrosion happening, etc,..but I was also asking about the purpose of the extension piece of pipe,....I guess no one in the know at the time happened along at the right time to help me out on that, cause I hadn't seen anyone mention that the real purpose of the pipe was to help prevent gasket blowout,....certainly makes sense however, I had more envisioned it's purpose as centering the exhaust pipe to the manifold as the exhaust pipe flange holes were 1/2" and the exhaust manifold holes were smaller at 7/16",...anyway - as PLYJM mentioned, I'm definitely past that now,....

 

I suppose if I have issues and can't keep a gasket in the flange, maybe I can have a short piece tack welded in later, 

 

I've been blocking the gasket surface side of this flange with a large file as Plymouthy suggested, and I've almost got it to where a stainless draftsman straight edge ruler lays perfectly flush in all directions, with not even the slightest light showing through between the edge of the ruler and the flange surface...

 

I've got a Victor 5438AK 2 hole flat flange gasket which looks to be a good 1/16th inch thick and appears to have a thin metal layer sandwiched inside between the outer fiber material..so I can see where this gasket has enough depth to compensate for a bit of irregularity on the flange surface, but I felt my chances to eliminate gasket blowout and to try and have even pressure on my cast iron exhaust flange (as not to crack it), was to try and get the flange as true straight as I possible could.....I'm almost there, I can still see just a but of gap out on the very outer edges of the exhaust pipe flange,...I would say by the time I have it dead on flat, I will have made this 3/8" thick stainless steel a little over a 32nd " thinner in the very middle of the flange up close to the pipe, and course it's still almost it's initial 3/8" thickness out on the ends...

 

I've heard folks mention a flat gasket like this Victor 5438AK, but one that also has a sleeve that goes up inside the pipe, I wonder if that would be a possibility for my situation ? 

 

Steve

[Dave72dt]

Now that you've almost got the flange flat, how flat is the mating surface of the manifold?