2.9 vs 4.0 y pipe flange

[jtaborsky]

Wasn't sure where to post this.

Do 4.0 and 2.9 have same flange on their y pipe? I'm trying to figure out the exhaust on my 4.0 Bronco II. Will bronco ii exhaust bolt up to a 4.0 y pipe?

 

[Shran]

If your Y pipes both use this style of gasket, then yes, it should.

I am in the process of building the converter side of this on my plasma table. Basically it will be a flat piece that will bolt up to your Y pipe and allow you to use an aftermarket converter rather than the oval shaped nonsense. If you are interested in one let me know, you can be my guinea pig

 

[gaz]

@jtaborsky
In 1988 Ford changed the 2.9l collector pipe from a dual circular outlet "H", to a 2-1 oval outlet "Y". You can use the 2.9l "H" with your 4.0l, this permits using the stock exhaust.

If you are trying to use the 4.0l's 2-1 oval outlet, it will not bolt onto the BII's stock exhaust without some modification.

 

[jtaborsky]

If your Y pipes both use this style of gasket, then yes, it should.

I am in the process of building the converter side of this on my plasma table. Basically it will be a flat piece that will bolt up to your Y pipe and allow you to use an aftermarket converter rather than the oval shaped nonsense. If you are interested in one let me know, you can be my guinea pig
View attachment 95807

Will it be a flat flange with a round outlet to clamp a universal cat onto, or is welding required?

@jtaborsky
In 1988 Ford changed the 2.9l collector pipe from a dual circular outlet "H", to a 2-1 oval outlet "Y". You can use the 2.9l "H" with your 4.0l, this permits using the stock exhaust.

If you are trying to use the 4.0l's 2-1 oval outlet, it will not bolt onto the BII's stock exhaust without some modification.

Good info. If I use everything after the y pipe from a 1989 or 1990 Bronco II, will that connect to 4.0 y pipe?

The reason I asked this question is the studs on my cat flange are too rusted to thread a nut onto them. Has anyone successfully rethreaded those studs for a smaller nut? My dad is a patient man, but I can tell he's getting sick of me taking up space in his shop!

 

[gaz]

@jtaborsky ,
The fasteners that bolt the component/sections together can easily be replaced with new fasteners. Just buy some new bolts, washers and nuts.

I have rebuilt Ranger Based Vehicle (RBV) exhausts a few times and never needed to weld one component. Anything can be connected with fasteners or exhaust clamps.

The exhaust from a 88+ 2.9l (Y style), will bolt right onto an OHV 4.0l Y-pipe.

 

[Shran]

Will it be a flat flange with a round outlet to clamp a universal cat onto, or is welding required?

Pardon the crappy picture but this is basically what I am building, minus the studs pictured. I have a few of the flat plates cut already and I could send them like that & you weld a piece onto it to go from oval to round - pretty easy - or I can do that for you and it would look similar to what I did below. Then you can weld or clamp a universal converter to it.

 

[Dunk67]

Anyone make a flange to attach exhaust to either pattern? Seems a lot of work for every one of us to one off these flanges and oval pipes, for what should be a relatively easy to make piece.

 

[gaz]

@jtaborsky ,
HELLO,
If you are still.in need if a solution, I HAVE IT.

Just include my @gaz in your response... I'm on here every couple days or so

 

[gaz]

@jtaborsky ,
Here are a couple pics of both flange versions (flange after the manifold pipes, prior to the cats). The oval is from 88+ and the dual 2" is from 86-87.

You may or not be able to see it but the bolt holes nearly align between the 2 flanges; the 2 holes to the right are only ⅛" farther, center to center. Also worth noting, they both use 2" tubing but the oval squishes out some volume from each.

I always thought that it was interesting that Ford had it set up for cross bleed (the H pipe [86-87 version] has a connected passage, where the O² sensor screws in) true dual 2" exhaust but instead sold dual to single???

 

[Nick Noble]

Pardon the crappy picture but this is basically what I am building, minus the studs pictured. I have a few of the flat plates cut already and I could send them like that & you weld a piece onto it to go from oval to round - pretty easy - or I can do that for you and it would look similar to what I did below. Then you can weld or clamp a universal converter to it.

View attachment 95957

Im interested in one of these was wondering if i could get one?

 

[Shran]

Im interested in one of these was wondering if i could get one?

Yep, I have a few on hand. $65 plus shipping for a complete assembled piece, $25 for just the flat flange (DIY version)

For Sale - 4.0 OHV Exhaust/cat flanges

I am building these as a side project to hopefully make doing your own custom exhaust a little easier - or maybe your catalytic converter was stolen and you are having some sticker shock at the price of a new one... whatever the case is, using an aftermarket catalytic converter is usually...

www.therangerstation.com