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Discussion Starter #1 (Edited)
I ordered a set of 2" headers for the new build - thanks Matt @Lt1z - and they got here in 2 days.

Overall they look good, but the mounting flange is less than uniform (see pic).

Still good to go with a GM gasket or do I need to get this milled?




For posterity: I get 0.020", 0.013" clearance on two primaries with the headers torqued down (no gasket).

This is perfectly normal, deal with it.

 

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Discussion Starter #2
The ARH flange looks like it was machined after welding, even after countless heat cycles as being used in this photo.

The SW looks like someone took an angle grinder to it.


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Can you clean your level? I can't look at it like that.....it's distracting.

Thnx
 

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Discussion Starter #5
Nothing says flat, quite like 250ft-lb on the rattle gun.
250 ft-lbs on an M8 bolt? :D

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As always, I vote torch and BFH!

It’s probably not going to make it flat but it should get out some of your frustration with hitting walls on the project!

Did you try calling matt to get his opinion?


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Permatex Hi-temp RTV - you'll be just fine..................................................changing headers is easy anyway, so what are you worried about...........
 

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Cut the flanges in half The 2 pieces will be flat when bolted to the head. See red line.


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Man those fuckers aren’t cheap, they should be close to perfect. How big is the actual gap, it doesn’t look really bad...
 

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Discussion Starter #12
Cut the flanges in half The 2 pieces will be flat when bolted to the head. See red line.


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The biggest gap is between cyl 2 and 4 - with the outermost bolt hole on #2 having a notable curve to it - so I'm questioning the cut between 4 & 6 having any effect there.

I haven't put feeler guages on it yet, but I'd estimate the gap at around .75mm or so.

And seriously, these things were $1700 so I expected to NOT have to deal with warped exhaust flanges on a product that has been out for 6+ years.

It's headers advertising 101: they're guaranteed to fit your car AND we use 3/8" flanges for a perfect, uniform seal!

I guess I will call them today and see what the excuse will be.

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I have the same headers. Stock steel gaskets with silver high temp RYV. Coat gaskets, let it dry for about 10 min then bolt on. No issues.
 

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Discussion Starter #14 (Edited)
I have the same headers. Stock steel gaskets with silver high temp RYV. Coat gaskets, let it dry for about 10 min then bolt on. No issues.
Did you have the same warped flanges?


With the manifolds snugged onto the heads, at the exhaust port of the head (ie inbetween the bolt locations), I'm getting clearance of 0.013" on one port, 0.016" on a second and 0.020" on a third with the feeler guage.

To complicate matters, the flange is not uniform: it looks like they smoothed out the welds with an angle grinder, leaving an irregular surface to mate to the gasket with.

Seems like a lot for the gasket to compensate for, and again slightly annoying from a quality control standpoint.

But I am looking for opinions so thanks for that.

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stock gaskets, no spray or sealant of any type . youll be fine.
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Discussion Starter #18
im going to go out on a limb here and say that the speed engineering headers dont have this issue :)

had to
Honestly, the ARH headers were good - their primary design is what limits the use in 6 bolt heads; and their flange is straight even after years of use. except I had one of the ARH hi-flow cats rust through due to how the pipe was made, and they said no warranty because I had them ceramic coated... so that was a "fuck you" for buying American and expecting customer service.

Kooks will fit, they confirmed that today but I've no personal experience.

Ergo I chose SW because they were a known header with these 6-bolt heads; I figure I'd give them the benefit of the doubt after reading through that sticky on their cat-back design, and here we are. The flange *might* seal with an OEM gasket, that's good. Or I could try some premium copper gaskets, etc to make it work. But I'm going to spend another $500 to have these Swain-Tech coated so I'm more than a little irked that it will be a bit of a wait and see until after the coating, where there will be no warranty, for what doesn't seem right from the get-go. Now in all fairness I am talking to SW, and they will review and get back to me - but I also paid a little more to use a site Vendor to avoid delays. lol.

So I suppose it's just the principle of it to buy a premium product for quality, and getting slip-fit connections with irregular mating surfaces. I'm getting the vibe that "it's good enough" from the feedback here as well as vendors, so yeah... "good enough" at half the price point might make more and more sense, depending on how SW handles this.
 

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I get your frustration totally...that said you can use a GM gasket and be good Im sure...See what they will do for you as its definitely unacceptable.


The gasket I used was a multi layer steel...the amount of gasket ring around each port is thicker than .030" when crushed...which is your irregularity. But then again...will it leak with time?
 

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As I mentioned in the PM I would expect they would just swap them out for another set which may have a better flange, but probably won't be checked before sending the replacement out. My guess is that it will seal with a GM MLS gasket, but ARH and Kooks do tend to have a bit better QC in my experience. If you want to return them and do Kooks instead we can also do that. Let me know
 
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