It seems to happen from time to time in the late model C6 with more than one header manufacturer. The headers occasionally hit the frame of the car.
Here's a picture of the usual problem on another car.




My car pictured here:



In my case, it's the same right side frame problem, and as you can see in the picture, in my car it's real hard against the frame.
The header bolts directly to the head, so obviously there is no real direct adjustment that can be done in this area. Using the search, I've come across several solutions.

(1) Contact the manufacturer. They will most likely exchange them for some that clear.
Most if not all of the big names stand behind their work. The issue with an exchange is that except for the opposite header that stays on the car, you end up doing almost all the job over. Not fun.

(2) I read that there is some play depending on where the engine is mounted on the engine mounts. One "trick" I've read with header rubbing problems is to loosen the two bolts that hold the motor mounts to the cradle and adjust the motor towards the drivers side.
This fix has me a little concerned. Would moving the engine present any long term strain on the torque tube or drive components?

(3) Minor "clearancing" of the sheet metal lip on the passengers side may done as the lip is said to protrude off the frame inconsistently.
Seeing where those spot welds are, I don't see that a lot of "clearancing" cam be accomplished. Plus, grinding on an expensive sports car, is distasteful.

My questions to the Corvette Forum hive mind: How much clearance would you demand for trouble free miles of driving? 1/4 inch, 1/2 inch?

What are your suggestions for the fix? 1, 2, 3, or a combination of 2 & 3? Or is there something I've not read of yet?

Thanks for the help!

 

Sorry to see you're having an issue. I had my tuner install my headers and I've had no problems. I have the LG longtubes.

I don't really have any constructive advice, other than to contact the header manufacturer. Best of luck.

San

 

I've also seen people simply take a crow bar and slightly bend the header away from that spot a little, it might then make installing the X-pipe a little more difficult (tight) but that's the beauty of a ball flange set up (on headers that utilize a ball flange connection that is).
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fn, easy fix I wish I had known earlier. Would have been easier prior to installation. You can take a pair of Channel Lock or Vise Grip pliers and bend the lip out of the way to allow clearance for the header tubes. If you mark the paint, just take some black gloss paint and touch it up and you are good to go. I would say 1/2" of clearance would be more than enough. If you ever want to return the car to stock, you can easily bend the metal back to the stock position, touch up the paint and nobody would ever know you had been there. I had the same problem when installing my headers and took a grinder to the metal lip and removed metal to within about a 1/4" of the spot welds. It now has plenty of clearance and no bent metal on the frame. If I had it to do over, I would bend the lip out of the way. Good luck!

 

You should loosely install the whole system before torquing anything down. You'll get a bit of leeway to play with to get any adjustments right.

Other than that, nothing a pry bar won't fix. ...and 1/2" is plenty. 1/4" is plenty too.

 

That is a common interference point at that pinch weld. You can take an air powere reciprocal saw and slice away through the middle of the welds that you can see, there is no problem with any structural issues as long as you cut on the outside of the weld or just through part of it. If you are worried about structural issues you can cut it, then wire feed weld it again. I have cut several of these pinch welds taking up to .250 from that lip area with no adverse effect.

 

Or use a hammer to bend the extra material after the weld back. I think this customization is necessary for a lot of header installs. I know my AR required it. Seems it is always the passenger side.

 

There are many posts about this on CF too. Seen it myself, it looks like an allowable mfg tolerance on GMs part, its in an area that doesn't affect anything when stock. Easiest thing to do is as 1Corvette said just bend the lip out of the way......a lot easier to do before the headers are on.

 

I had this issue on my C5 with the Kooks 1-7/8. Nothing a little hammer massaging cant fix, some opt to grind on the lip a little. Either way, 6 to one, half a dozen to the other.

 

Intriguing. Riddle me this; If the header to exhaust port surface has to meet square, and the bolt holes on the header aren't slotted, doesn't this mean that there is no adjustment possible on the header itself?

May I ask what I'd be prying on? Would that flatten the header and bend the flange at the same time? Would it be wise to pry on a ceramic header?

 

Personally I wouldn't pry on the headers that are bolted to your aluminum heads, I used an air powered cutting wheel and took off about an 1/4 inch and primed and painted it afterwards. My headers were in place already just as yours are when I performed the fix.
Almost two years later and they have never rubbed/touched the frame.

 

don't mess up a good header when there is a simple solution. I know it sucks to have to make the car fit the header, but its better than knocking a dent in a costly pipe when you can easily make room for it.

 

I've read several people say here that there is some play depending on where the engine is mounted on the engine mounts. One "trick" they've written with header rubbing problems is to loosen the two bolts that hold the motor mounts to the cradle and adjust the motor towards the drivers side.
Has anybody tried this??

The only thing that has me a little concerned, is whether moving the engine presented any long term strain on the torque tube or drive components?

 

Just bend it with Channel Locks. If you go back to stock, bend it back. That's what I'm going to do if I have the issue when I install my ARH's which are sitting in my garage awaiting install. As far as doing something with engine mounts, that sounds like a non-starter to me.

 

I would think if you have any of the made in USA brands they would get you a new one asap. What I would do.

 

Seems if your prying something in front it has to bind something out back... for every action there is an equal and opposite reaction - Newton’s law

 

This is very common problem and very easy fix! Remove to do choice number 3. If the grindings are not tasteful I wouldn't eat them!
Seriously now that is where the floor pan is seamed together. I was able to easily trim it back. You can cut it back or grind it down then
spot paint it with black spray. Then install the header.
Had the same concerns on first install. It is really No issue!
Removing even a 1/4 inch goes along way!
You can grind it back in to the spot weld if you like no worries.

 

Based on the number of suggestions that recommended trimming, I decided to trim where the floor pan is seamed together. I was able to easily grind it down a little over 1/4 inch then spot paint it with black enamel. Then I reinstalled the header.

Thanks to everyone who offered suggestions in this tread.

 

do the motor mounts first then if you need more loosen the sub frame bolts adjust clearance, then tighten back down, get a new alignment.

-Carl