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  #1  
Old 04-28-2021, 11:59 PM
Waggymcgee Waggymcgee is offline
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Location: Outside Spokane, WA
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catalytic converter? - yay or nay

Need a whole new exhaust system. Thinking about removing cat converter and air pump. No emissions required in this state but I am a bit of a tree hugger.

If I do remove should I keep them for any future owner?

Appreciate your input.
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  #2  
Old 04-29-2021, 12:43 AM
Dave Jeeper Dave Jeeper is offline
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I replaced my exhaust from the cat back to the tailpipe a couple of years ago. I ordered my parts from Rock Auto and the cat wasn't that expensive. It had an air pump connection on the cat but also came with a small cap that I welded on since I had removed my air pump as part of my Howell Fuel Injection installation. I saved all of the air pump stuff that I took off along with the carb in case a future buyer wants it.


Parts can be had for not that much if you mail order and install yourself.


The original Grand Wag exhaust parts are very thick stainless steel. I only replaced my cat converter because the inside material had cracked and was rattling around. The metal was still good.



My 2 cents.


Dave
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  #3  
Old 04-29-2021, 08:20 AM
MysticRob MysticRob is offline
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Join Date: Nov 26, 2019
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I really hate the smell of unburned gas exiting the tailpipe so I'm a big fan of leaving that stuff on there just to clean the exhaust gasses a bit, unless you're going fuel injection and it's no longer necessary (points finger at self).

You never know when you're going to need that stuff, like if you decide to sell it to someone who lives in Smogifornia, etc. I'm keeping all my smog stuff in storage just in case. I was joking with Dave that you never know when/if that stuff will be so rare it fetches thousands of dollars like old Thermactor gear on Boss 429s.
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  #4  
Old 04-29-2021, 10:50 AM
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tgreese tgreese is offline
 
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Supposedly there are replacement cats that do not need the flow of fresh air from the AI pump. Might be what you are looking for.

Also supposedly - the air pump will rust internally and freeze up it you remove it and put it on a shelf. I've read you can dunk them in kerosene or immerse them or something and they will be preserved.

Removing the extra systems probably will prevent sale of the car anywhere that requires a visual, like California or places in Arizona and Nevada ... maybe others.
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  #5  
Old 04-29-2021, 11:05 AM
61Hawk 61Hawk is offline
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I found a replacement that didn't need the air pump, direct fit in with a brazed on cap over the air pump inlet. Installed it, pulled the air pump that had recently locked up, and haven't had a problem since. The old catalytic converter was the original and when I pulled it off was completely hollow inside. I can now put my nose up to the exhaust pipe and breath without any gas fumes.
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  #6  
Old 04-29-2021, 02:04 PM
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Herk Herk is offline
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The modern honeycomb catalysts have basically no restriction and cost no power. The original pellet type catalysts that our vehicles came with were another story.


The air injection system does use a little power and clutters up the engine compartment. Modern cats will fire off fine without it if it is mounted in the original location.
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  #7  
Old 04-29-2021, 05:29 PM
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Tripwire Tripwire is offline
hey,does anyone here know how to.......
 
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yes install the Cat, you dont need outside air and the planet will be a bit better for it - as said they offer very minimal restriction

steve
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  #8  
Old 04-30-2021, 06:57 PM
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ProTouring442 ProTouring442 is offline
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I recently installed a cat on my LY5 swap. While the exhaust on my swap is probably cleaner sans cat then a stock Wagoneer's is with it, I like the lack of exhaust smell, plus it quiets it a bit.
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  #9  
Old 04-30-2021, 08:12 PM
Waggymcgee Waggymcgee is offline
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I kept the cat new exhaust. Flow pac. My little one said, the jeep sounds furious. Hell yeah.
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  #10  
Old 05-07-2021, 12:39 PM
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rang-a-stang rang-a-stang is offline
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Quote:
Originally Posted by Waggymcgee
I kept the cat new exhaust. Flow pac. My little one said, the jeep sounds furious. Hell yeah.
Does this mean you put a new cat on there? A furious Jeep is much better than Jeep that sounds like a Prius...
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Old 05-07-2021, 12:55 PM
oregonphil oregonphil is offline
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So just for discussion sake, if we agree that cats are better for the environment, would there be any downside to voluntarily installing one on older cars that did not originally come with them? Not counting the extra cost and labor.
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  #12  
Old 05-07-2021, 02:01 PM
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ProTouring442 ProTouring442 is offline
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Quote:
Originally Posted by oregonphil
So just for discussion sake, if we agree that cats are better for the environment, would there be any downside to voluntarily installing one on older cars that did not originally come with them? Not counting the extra cost and labor.

Yes! An engine not properly tuned for a cat can cause the cat to overheat.
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Old 05-07-2021, 04:36 PM
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Heavy_Metal_Thunder_81 Heavy_Metal_Thunder_81 is offline
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I'll be running dual cats on mine soon.
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  #14  
Old 05-10-2021, 11:59 PM
Waggymcgee Waggymcgee is offline
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Quote:
Originally Posted by rang-a-stang
Does this mean you put a new cat on there? A furious Jeep is much better than Jeep that sounds like a Prius...

I kept the cat that was on there which is just a catco, but she is running great. Had been stalling primarily when turning right so thought it needed carb work. Did not want to mess with carb til I had the extra fuel tank working right. But, she has not stalled since replacing all the fuel lines. Hooray!
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  #15  
Old 05-11-2021, 10:05 AM
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rang-a-stang rang-a-stang is offline
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  #16  
Old 05-16-2021, 02:15 AM
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FSJunkie FSJunkie is offline
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I have no problem with a converter so long as it's not restrictive, which a good cat isn't. I like how they quiet the exhaust down further, too.

However, a recent experience reminded me that converters and carburetors should never mix:

The ignition coil wire came loose on my Eagle's 258 at 70 miles per hour, cutting off the ignition. The moving vehicle kept turning the engine, pumping raw fuel through the engine and into the exhaust because the carburetor had no idea the ignition cut, so it kept feeding fuel. Well, all that raw fuel hit the hot converter bed within seconds and......BOOM! Glowing red chunks of my exhaust system blasted out the back and bounced down the road as I coasted to the side, dead, no restart, 800 miles from home, on vacation, in the middle of BFE. Have you ever been to Greensburg, Kansas? That's where I was.

Not to mention carburetors are often too rich in some situations just as a part of their nature, which works the cat harder, overheats it, shortens it's life, or plugs it. The same thing is true for the higher oil consumption that is an inherent part of older engine designs. The oil slowly poisons the cat. Converters produce heat and water vapor, which cooks or rusts the rest of the exhaust system around them.

I would rather not deal with all of that, especially the IED that my converter became when it received a massive dump of raw fuel from a loose ignition coil wire.

I put small second mufflers or resonators in place of converters now. No more for me.
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Last edited by FSJunkie : 05-16-2021 at 02:21 AM.
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  #17  
Old 05-16-2021, 07:07 AM
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Brynjminjones Brynjminjones is offline
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Interesting story, doesn't sound like a good situation!

One question I had - do new cars actually cut fuel if they know there is no spark?
We have a few of the later Jeeps with the fuel injected 4.0 in the family, and those certainly don't.
My dad's ZJ once had a bad spark lead and managed to flood itself badly enough that it wouldn't start even after getting the spark back!

Back in my college days, my friends and I pulled leads on my 4.0 XJ to see how many cylinders it needed to run. We got it down to 2 cylinders, and it was spitting fuel out of the exhaust!
Funny enough, next emissions test I needed to replace my cat.


I'm considering adding a cat to my FSJ too. I'm fed up with the gas stink, and I can get a cheap, non-restrictive cat for about $70.
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  #18  
Old 05-16-2021, 09:20 AM
61Hawk 61Hawk is offline
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Interesting that catalytic converters and carburetors should never be used since catalytic converters started being used on the assembly line in 1975 when if most if not all gasoline powered vehicles were carburated.
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  #19  
Old 05-16-2021, 11:51 AM
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rang-a-stang rang-a-stang is offline
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Quote:
Originally Posted by FSJunkie
....especially the IED that my converter became....
BBWAHAHAHAHAHAHHAH!!! That phrase is awesome!!!
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