New stock exhaust install & cat questions

[Timothy]

Ok, so I got a Walker resonator and muffler showing up to my house tomorrow.

The problem: How to attach it to my current catalytic converter. I developed a loud exhaust leak where the downpipe connects to the cat. There were two failed and badly rusted flanges with spring bolts and a donut where the downpipe and cat connect. The down pipe is 1 3/4 going into a 2" flared out pipe that accepts the donut gasket on the cat inlet.

I cut off the existing resonator about 3" down from where it was welded onto the cat. There were no mating flanges.

I would like to reuse this cat. The inside looks fine and nothing rattles, except for all the gravel that was trapped under the heat shield. There is currently a 2" diameter pipe welded to the outlet.

I'm assuming the Walker resonator will be 1 3/4 diameter. So My best idea so far is to buy a 1 3/4" to 2" adapter and shove the 1 3/4 end into the resonator and the other end onto the cat and clamp them together. The only thing that sucks about this is the pipe on the cat outlet is old and rusty, although it still seems to be functional and thick

OR I could some how grind the pipe all the way down until it is flush with the flange that's already there and then mate it with the resonator with its flange and throw a new gasket inbetween the two.

Another thought is just deleting the cat all together. It is currently not on my car and I have experienced better gas mileage but the downside is the exhaust was a bit louder and the smell coming out the exhaust is a bit noxious.

Any ideas, and is my current plan a disaster waiting to happen? I've attached a photo of the cat where I cut it near the flange.

IMG_0553.jpg

[Shin Hayata]

We have annual emission inspections in PA; exemptions are provided only if the vehicle has 5K or fewer additional miles on the odometer since the date of the prior year's inspection. I'm driving the heck of my recently-acquired 88L, so I don't know if I'll be under or over the 5K threshold come Spring when the inspections are due.

By way of example, I have two motorcycles: one with FI and a cat, and one with a carb and a muffler (no cat). The former's exhaust literally smells clean; the latter, a bit more old school but still relatively tame. I use the Festiva as well as both bikes for errands as well as pleasure driving/riding. Stop-and-go traffic is part of the equation. Summertime brings out the Harleys and their straight-piped nonsense. Noxious noise, noxious exhaust smell. I don't want to contribute to that sort of pollution in any way, at any time.

Long story longer: The picture of your catalytic converter suggests that it's pretty long in the tooth. Were I in your position, I'd replace everything from the downpipe back with new components. Period. The car was designed to function with those fitments in place, and again, I have the specter of state safety and emission inspections to consider. It seems you do, also.

[Timothy]

Luckily in Missouri cars built prior to 96 have no emissions requirements.

I totally agree that it would be best to just replace it all together. I have found cats for as cheap as $35 on Amazon that are non CARB compliant. I would love to just put in a new one. So maybe I can look into that in the future, but for now that is $35 I don't have.

Thanks for your input and story about your motorcycles.

[F3BZ]

feel your pain. old rust belt cars are so much harder to work on. i swear i must have an old cat in good shape i'd let go cheap but soo many parts in soo many places. i'll try to remember or maybe someone will have one. man i really hate to see you have to make that work.

[Timothy]

feel your pain. old rust belt cars are so much harder to work on. i swear i must have an old cat in good shape i'd let go cheap but soo many parts in soo many places. i'll try to remember or maybe someone will have one. man i really hate to see you have to make that work.

Thank you for the offer. Sounds like your garage is as well organized as mine. Haha.

[Timothy]

So I installed the new muffler and resonator. Unfortunately, despite my best efforts, the cat didn't make it. I cut and grindef that pipe on the cat so it was Flush and then grinded the flange until it was smoother. I put everything back together and exhaust gas was shooting out the side of the car.

So my system from the downpipe goes as follows. 8" 1 3/4 braided stainless steel flex pipe, 1 3/4 od to 1 3/4 id adapter that I hammered into the Walker resonator, then the resonator, and then the Walker muffler. The upper custom portion is held together with exhaust clamps.

Sounds... Meh... Tinny and raspy between 3000-4000 rpms. It's definitely better than what was there before. It was a 2" system that was rusted through at many points. Highway drone is considerable better too. It sounds good and quiet at idle. In the future I plan to buy and install a new cat. It should mellow out the sound a lot.

[Timothy]

Does anyone know why this cat wouldn't work with my car. It is 1 3/4" ID. I think it would work great. The only thing I can think why it's not recommended for me is because the OAL is less than a stock one. But that's no big deal.

The ones that are recommended have a 2" ID I think. Also this one doesn't have an air tube. I really don't understand what that is ( other than the basic info google reveals)

http://m.ebay.com/itm/181848899519?_mwBanner=1

[FestYboy]

The EFI cars don't get the air tube. That car should be fine if you can get it sealed.

[Timothy]

Awesome. Thanks for your help Festboy!

[Timothy]

My new cat came in the mail. But alas I have problems. It has an overal legit of 13" and my flex pipe has an overal legnth of 8" even though it was advertised as 4".

My original plan was to attach a braided stainless steel flex pipe to the intermediate pipe ( because the original flange holdings the spring bolts rusted off) and then the cat to the flex pipe. There is only 14" of open space to fit this in and the flex pipe and cat is 20". So a part of my original plan was to just lop off 6" of the intermediate pipe and everything would fit perfectly.

However the intermediate pipe makes a lateral bend in the space I was planning on cutting, causing my whole grand plan to fall apart.

Someone tell me how stupid would it be to omit the flex pipe. Trying to think of ways to make everything fit.

[ryanprins13]

My new cat came in the mail. But alas I have problems. It has an overal legit of 13" and my flex pipe has an overal legnth of 8" even though it was advertised as 4".

My original plan was to attach a braided stainless steel flex pipe to the intermediate pipe ( because the original flange holdings the spring bolts rusted off) and then the cat to the flex pipe. There is only 14" of open space to fit this in and the flex pipe and cat is 20". So a part of my original plan was to just lop off 6" of the intermediate pipe and everything would fit perfectly.

However the intermediate pipe makes a lateral bend in the space I was planning on cutting, causing my whole grand plan to fall apart.

Someone tell me how stupid would it be to omit the flex pipe. Trying to think of ways to make everything fit.

For me anyway a picture would help a lot. I want to say buy a shorter flex pipe but i have a feeling that the reason your asking is because that wont work?

Sent from my SM-G920W8 using Tapatalk

[Timothy]

Thanks for your help ryanprins13. A photo is incoming and I'll post one soon. The flex pipe that in bought ( https://www.amazon.com/gp/aw/d/B017A...?ie=UTF8&psc=1 ) comes in a smaller size with the extension pipes on either side of the flex joint deleted. That would save me 4" but then I would have to hire a welder, and I would not be able to use exhaust clamps.

Thanks again for your help. I'll post better visuals soon.

[Timothy]

IMG_0640.jpg

[Timothy]

Ok it's all out together. I hope it will last a long time.

So I cut 3" off the intermediate pipe, then the 8" flex pipe , the the cat, then I looped 3" off the resonator pipe, and then everything downstream remained the same.