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Discussion Starter #1 (Edited)
So my catalytic is obviously broken inside, it makes an awful rattling noise when idling, upon inspection i have 2 converters and the line coming from the EGR is also broken and not attached to the cats.
My FSB is is an 89 and i have vintage registration not requiring emissions anymore, so what can i do with that catalytic, can i just chop it out? do i need to use an EGR delete? is there a bolt on option without the cats? do i just put a new cat in? I'm not against having a cat installed just want to fix the horrible noise either way.

Any thoughts?
 

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95 Bronco, 351W, E4OD, 4.56 gears, 35x12.50x15 Patagonia MTs. 94 Bronco 5.0/E4OD/1356/3.50 gears.
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These old trucks and modern cats work very well together. If possible, put on a new cat and call it a day. It won't effect your power, and it will help reduce pollution. If you want more power later, or to avoid any restrictions, just weld in a larger cat for more flow potential? I had a 3"cat on installed on a little 240SX (145 hp 2.4 4 cyl) years ago, made no difference in power with or without it so I left it on.
 

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85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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Cut em out, leave the egr in place, but you can remove that air tube leading to the first cat. Preferably you'll replace it with a modern 3-way.

On my 85, in KS the land of no smog checks, I put a 3" magnaflow spun metallicat on it. High flow, nearly no sound reduction, and high fume reduction.

Put a cat back on, regardless of testing. Its better for your health and everyone else's.
 
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Discussion Starter #4
Cut em out, leave the egr in place, but you can remove that air tube leading to the first cat. Preferably you'll replace it with a modern 3-way.

On my 85, in KS the land of no smog checks, I put a 3" magnaflow spun metallicat on it. High flow, nearly no sound reduction, and high fume reduction.

Put a cat back on, regardless of testing. Its better for your health and everyone else's.
What is a modern 3-way?
Any recommendation on where to get a Y pipe? my first cat has two inputs.
 

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What is a modern 3-way?
Any recommendation on where to get a Y pipe? my first cat has two inputs.
I honestly dont know. I know the old ones, like what were stock, were 2way and required the air injection. The newer ones dont need the air.

Theres a few y-pipes available, the best being magnaflow or flowmaster. You must get the one for your engine. 302 and 351 are different in this aspect.

I made my own y-pipes so I cant say I have any experience with the others.
 

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You have to put on a bassani or walker or catco y pipe or make a new y pipe from your old one. Catco sells universal cats that are high flow. Would be equal to the bassani exhaust in 3".

Old oem cats are worth money in scrap. could be up to a couple hundred if sold to the right buyer.
 

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Discussion Starter #7
I made my own y-pipes so I cant say I have any experience with the others.
If I were to make my own where do you get the pipe stock?, pre-bent elbows?
 

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If I were to make my own where do you get the pipe stock?, pre-bent elbows?
I bought my supplies from summit racing, but jegs also has it all.

I planned my routing out, then bought some mandrel bends, straight pipe, flowmaster y-collector, and the correct flanges to hook to my headers.

Then you'll need a welder and some way to cut the pipe and bends. A chop saw is good, but even a grinder or hacksaw will work.

Take your time, and work from the headers back. Keep it tight up to the body. Use a few hangers to keep it sturdy. Use a flange or slip joint somewhere in the middle so it's easy to install and remove.
 
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THe magnaflow is a nice piece. I put one on a 91 f-150. The cat comes with it seperate.

The older cats needed 2 materials to do the same thing the new one do with 1. That is why you have 2 stock. Or at least what I think is the reason. The air pump was only their to help heat up the cat (to my knowledge), at start up. If you go to the magnaflow y-pipe, for example, it will have a 3 way cat, and no air injection needed. The f-150 I mention also has the air pump removed, but the EGR still in place and fuctional. Works great.

I am not pro or anti cat, I will say that if you use your Bronco to haul trailers it is nice not ot smell the exhaust when getting them hitched up, like-wise the fumes maybe less (smell) if back window down and such too. I have vehicles with and without them. I put 1 back on my f-250 for the trailer reason.
 

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Discussion Starter #10
I bought my supplies from summit racing, but jegs also has it all.

I planned my routing out, then bought some mandrel bends, straight pipe, flowmaster y-collector, and the correct flanges to hook to my headers.

Then you'll need a welder and some way to cut the pipe and bends. A chop saw is good, but even a grinder or hacksaw will work.

Take your time, and work from the headers back. Keep it tight up to the body. Use a few hangers to keep it sturdy. Use a flange or slip joint somewhere in the middle so it's easy to install and remove.
Thanks for the info, I have a welder and tons of tools just no pipe bender.

I'm attaching some pics and would like your advice, I want to try and keep my current y-pipe and just hack it off where it meets the first cat and weld up a flow master y-collector directly to the duel 2.5 inch pipes. My current cat-back exhaust is 3 inch with cherry bomb muffler, I plan on keeping the muffler and tailpipe and just popping in a new single catalytic between the collector and muffler, what are your thoughts?
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I think that's a great plan. Judging by the pics, the CAT is rusty toast.

So first things first. You must keep the oxygen sensor in approximately the same place.

The flowmaster y-collector is my choice of junction pieces, but others such as magnaflow offer a solid piece too. The flowmaster is shaped different than every other one. The inlets are not straight, they angle out a bit, to ease in welding in a tight spot. They are also a secondary collector, boosting scavenging and adding a distinct tone.

Here's a pic showing my custom y-pipe, with the flowmaster Y. I then welded in a new bung to the y-collector for the O2 sensor. 2.25" into 3" though a flowmaster deltaflow 50 and out in front of the rear tire.





That's on my 96 f350, with a 351w. This next one is the one i made for my 85 bronco with a 300 inline 6 and longtube headers. You can see the O2 bung placement and my CAT. 2.5" into 3",



The cat is a magnaflow spun metallicat. It's high flow, doesnt reduce decibels much, and cuts the fumes down tremendously. View through the cat



It finishes out through a borla xr1 oval race muffler and a full 3" tailpipe. Full mockup

 

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Discussion Starter #12 (Edited)
I think that's a great plan. Judging by the pics, the CAT is rusty toast.

So first things first. You must keep the oxygen sensor in approximately the same place.
What if i cut the pipes where they connect at the cat? leaving the o2 sensor in place, cleaning up the pipes and welding straight to the collector? assuming the pipes aren't rusted to shit of course.

Sweet pipes by the way, i could only wish mine to look that nice! My truck is loud enough already, i'm thinking of a more conventional cat.
I only drive it about 500 miles a year so it doesn't have to be perfect.
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Should be fine doing it that way, if the pipes will line up right.

Yeah, mine is a small cat. But does what I wanted.
 

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Discussion Starter #14
Anyone know what kind of steel the original pipe is? also if i buy a bunch of new pipe for custom work does it matter what kind i merge with? i will be keeping some of the old pipe so i'm just making sure.
 

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It's just mild steel, I'd suggest replacing any tubing you can because the rusted sections will be thinner and more brittle than the new material.
 

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Discussion Starter #16
Ok, so my current rusty y-pipe is 2.5 inch OD, if I redo this should I just go ahead and and upgrade to 3 inch?
My current exhaust is 3 inch everywhere else.
 

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Discussion Starter #17
I think that's a great plan. Judging by the pics, the CAT is rusty toast.

So first things first. You must keep the oxygen sensor in approximately the same place.

The flowmaster y-collector is my choice of junction pieces, but others such as magnaflow offer a solid piece too. The flowmaster is shaped different than every other one. The inlets are not straight, they angle out a bit, to ease in welding in a tight spot. They are also a secondary collector, boosting scavenging and adding a distinct tone.

Here's a pic showing my custom y-pipe, with the flowmaster Y. I then welded in a new bung to the y-collector for the O2 sensor. 2.25" into 3" though a flowmaster deltaflow 50 and out in front of the rear tire.





That's on my 96 f350, with a 351w. This next one is the one i made for my 85 bronco with a 300 inline 6 and longtube headers. You can see the O2 bung placement and my CAT. 2.5" into 3",



The cat is a magnaflow spun metallicat. It's high flow, doesnt reduce decibels much, and cuts the fumes down tremendously. View through the cat



It finishes out through a borla xr1 oval race muffler and a full 3" tailpipe. Full mockup
After looking at the stock y-pipe a bit more i think it really needs replacing, I'm a little hesitant to try and fabricate one on my own but will. After reading other posts i think i'm leaning towards this guy: https://www.autoanything.com/exhausts-mufflers/61A2673A0A0.aspx the off road version.
Also i was curious about that metallicat, how do you like it so far? How much $$? also i like how small it is so its easy to fit under there. Also curious how much louder it would be?, i'm thinking i might be replacing the muffler while i'm under there and possibly just get one to cut some decibels that way. Any thoughts on that?
One more thing: the Bassani says it's stainless steel, is that ok to weld right up to my existing mild steel muffler and tail pipe?
 
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If the new Y pipe has a flange fitting, it would benefit you to weld a comptatible flange on your exhaust rather than welding the two sections together. Yes you can weld stainless to mild steel, but it won't be ideal by any means. Use a slip joint if you do for more strength.
 

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After looking at the stock y-pipe a bit more i think it really needs replacing, I'm a little hesitant to try and fabricate one on my own but will. After reading other posts i think i'm leaning towards this guy: https://www.autoanything.com/exhausts-mufflers/61A2673A0A0.aspx the off road version.
Also i was curious about that metallicat, how do you like it so far? How much $$? also i like how small it is so its easy to fit under there. Also curious how much louder it would be?, i'm thinking i might be replacing the muffler while i'm under there and possibly just get one to cut some decibels that way. Any thoughts on that?
One more thing: the Bassani says it's stainless steel, is that ok to weld right up to my existing mild steel muffler and tail pipe?
The bassani is a great piece. Worth the cost.

My metallicat was about $100 a few years ago. It does not muffle sound much at all. I went from no cat and a flowmaster 40, to my full new exhaust, with the metallicat and a borla xr1 race muffler. It got significantly louder, maybe 25%. The metallicat is made of stainless and welds to mild steel just fine.

Muffler choice is tough to recommend, as everyone wants and likes something different. I really like the delta flow 50 series from flowmaster. Mild and throaty until you step on it, then it gets louder. But nothing like the cackling 40 series. I have one on my 96 f350 with no cat, shorty headers, and custom, before the rear tire dump exhaust. Sounds great.

I also recommend utilizing a flange between y-pipe and the rest of the exhaust. Makea install and removal much easier.
 
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