FYI my new ATP Challenge Y header 101212 flange is too thick for the intake manifold and my problem seems to be the opposite of most others. I didn't measure it but I I will on Thursday

 

Having the same problem with my new ATP 101212 header. The flange is thicker than the intake manifold tabs. I contacted ATP and will report what they have to say. I can't imagine there aren't many more folks with this issue. Mine is on a 98 Cherokee Sport 4.0L. Thoughts?

 

Well, I ended on giving up on the 3-into-2-into-1 design myself, as mentioned earlier.
I didn't get as far as the ATP header ( tried two different suppliers of that design), and just went with the NAPA/Dorman improved-OEM design (with expansion pieces).

I suppose if you know someone with a quality shop belt sander and grind off the excess on the flange, if ATP won't refund you. I had the opposite problem, in that the flange was too thin.

There were two threads (including this one) on the topic this year, and it seems only the US suppliers had the problem of too much material on the flange. I can't find the other one--I must've unsubscribed.

I don't know if we collectively took measurements of the intakes, but I'm assuming they're all within a slim margin of error.

 

Thank you for your response! I purchased the header through amazon and they will refund my cost but I might just try and modify it first. I've also contacted ATP today but don't expect to hear back until after Christmas. The problem is where the flange needs to be ground is not easy to get to. A rotary tool with a flex shaft and tungsten bit may be necessary although my die grinder might fit in there too. I'll post an update with some pics soon.

 

As I mentioned below, i've contacted ATP to see what their response is to this ridiculousness. I'll post my findings. Other than grinding the header flange to match the intake, i'm thinking of cutting a dome washer in half to use a shim. I ordered some more from Quadratec :

OMIX-ADA 16919.32 Manifold Washer

I'll need to shim in 8 spots so I ordered 4 washers to cut in half. In the meantime, i'll cut a couple today and post the results with pics.