Which header brands have actual 2.5" exhaust opening?

[1984Laredo]

While compiling my parts list, I've come across something that apparently varies greatly among aftermarket headers. What header manufacturers out there sell a header that has a true 2.5" diameter opening at the collector flange? Some list specs that show it as 2.125", others list no specs at all. And others, such as Gibson (which I was really leaning towards until my interaction with their "tech" guy), could not even tell me what their size was. I had email and phone communications with their tech support, and all he could tell me was "it replaces OEM"...

It looks like Doug Thorley is a 2.5" outlet.

I'm not sure about Banks. I've read conflicting info on them. Does anyone have a definitive answer?

Gibson is out.

Any other reputable ones that are 2.5"?

[275/350 I-6]

I have a Banks Revolver Installed on my engine, that I just put in my CJ-7. When I got it, I measured it at 2.5”, and ordered tubing, muffler & a cat, plus some flanges to make the system removable for maintenance, it’s all 2.5”. After seeing your question, I looked into the size a little closer just be be sure.

The header & engine are installed, but the fenders & radiator/ grill are not, so I can still get in there pretty easy. I stuck a tape measure in there, but it’s hard to get it exactly where I want it, but is appears the widest diameter at the flange is 2.5”, but just a short distance in, it appears to drop down to something closer to maybe 2.25”.

The exhaust pipe I bought for the system is 2.5” OD. I believe it is safe to say the Banks Revolver has a 2 bolt collector flange with a 2.5” diameter.

This picture is the collector flange at the end of the header.

FC3FB6FF-38C8-41EA-B830-95C23C1B25FD.jpeg

[275/350 I-6]

This picture is the 2 bolt flange I bought for the system.

[275/350 I-6]

This is the same flange bolted to the header.

[275/350 I-6]

This picture is the same flange sitting on a small pieces of the 2.5” OD exhaust pipe, I welded them together for practice.

[275/350 I-6]

FYI...I am not going to use the flange in the pictures. The header comes with a donut to seal the header to the OEM down pipe. The down pipe has a small ring built into it that centers the donut, so it seals up with no leaks. I’m going to acquire a used pipe and cut the end of it off to use, so the donut is held in place. I will weld my pipe to the used flange that I’m going to cut off of the used down pipe.

I’ll post more pictures after I get the pipe, and I cut the end off of it.

One more thing, the Banks header is expensive, but it is well built and appears to be very hi quality. I don’t think it’s doing to crack like the others crack, but time will tell, concerning cracking.

[275/350 I-6]

One more picture of the Banks Revolver header installed on the engine.

9D5D178D-5007-4DC9-BE78-6DE9FCAEA74A.jpeg

[1984Laredo]

Thanks so much for measuring that and posting the pictures.

Btw, exactly which AMC Blue is that? I’m leaning towards that color on mine, especially since it’ll be going into a CJ7. I’ve seen a lot of different shades and variations of AMC Blue, but I think I like yours the best. Where’d you get it?

[275/350 I-6]

I bought it online from Amazon.

[275/350 I-6]

This paint looks nice in a well lite area. I know my 1985 CJ-7 came with a black engine. I had a 1986 CJ-7 new off the dealer lot, and it has a black engine to. I’ve had many earlier AMC cars that had blue engines, so I decided to put a blue engine in my AMC.

I put the engine/TF999/Dana 300 in as an assembly last weekend.

[Cam Hensley]

I have a Banks Revolver Installed on my engine, that I just put in my CJ-7. When I got it, I measured it at 2.5”, and ordered tubing, muffler & a cat, plus some flanges to make the system removable for maintenance, it’s all 2.5”. After seeing your question, I looked into the size a little closer just be be sure.

The header & engine are installed, but the fenders & radiator/ grill are not, so I can still get in there pretty easy. I stuck a tape measure in there, but it’s hard to get it exactly where I want it, but is appears the widest diameter at the flange is 2.5”, but just a short distance in, it appears to drop down to something closer to maybe 2.25”.

The exhaust pipe I bought for the system is 2.5” OD. I believe it is safe to say the Banks Revolver has a 2 bolt collector flange with a 2.5” diameter.

This picture is the collector flange at the end of the header.

FC3FB6FF-38C8-41EA-B830-95C23C1B25FD.jpeg

Do you remember where you got the 2.5" tubing from? Was it already fabbed for your jeep or just straight stock material that needed to be fit.