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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.
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242 Posts
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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Addicted to Junk
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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Addicted to Junk
85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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11,935 Posts
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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85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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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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