86VetteBill

I've checked the posts and archives, but couldn't find anything about how to gut the pre-cats and the main cat. I've got the rear y-pipe off and can see inside the cat. It looks like a loose movable piece of material. How do I go about gutting this main cat?

Now the pre-cats... THAT looks like a job and a half. I haven't removed the front y-pipe, so I can't tell you what I see in there. Is this something I should leave alone?



[Modified by 86VetteBill, 4:49 PM 1/11/2003]

Mike's 86

Hey Bill i'm in Willowbrook how you doing? I read in a post somewhere to use a pipe and break out the material in the cat then start it up and blow out all the crap. I could be wrong but i think that's how you do it. But i would get some feedback first, not sure if it will give great improvement and it might set a code without a cat. As far as the precats, try a muffler shop to cut them out and install a pipe. I have not done exhaust mod yet but was thinking on highflow main cat and a catback sys. :cheers:

86VetteBill

Hey Mike! You're real close - I'm by I-88 and Rt 59. I can try that pipe suggestion on my rear cat. I'll see if there's any other responses. My new(er) y-pipe and 2 mufflers are being shipped soon from CLUTCH^Master in Virginia - they only have 8k mile on them and they're GM parts. So I'll have a few days to play with the my main cat until they arrive.

I see you have a Heritage Springer. :cool: I took my '98 Dyna Wide Glide out to Sturgis last year and am going back this year. Call and we'll get together to ride and check out the Vettes. 630-369-6611 :cheers:

Mike's 86

:cool: I'm at Rt83 & 63rd. Will call and hook up :cheers:

Black85L98

I do not know about your pre-cats but the main cat can be busted apart with a pipe or long rod. I used a shop vac to clean mine after I busted it up. It takes a little time. Make sure you mufflers are off if you blow it out with exhaust.

86VetteBill

Good info - I'll do the pipe thing since that seems to be the consensus. Since I've already got the rear y-pipe off, I can blow it directly out the cat.

But if the pre-cats are getting clogged (76K miles) it won't matter how open the rest of the exhaust is. :banghead:

Phobos84

A friend of mine got real board and gutted my cat for me. She just took a fire poker from my old coal heater and a rubber mallet. It took her like 20 minuets to get it all out. It made a mess on the floor but was well worth it. :cool:

VetteNoob

shouldnt throw any codes. i had a muffler shop cut my pre-cats off and my cat was already gutted. you may want to take the cat off to beat the crap out of it to prevent from shooting cat guts into your front y pipe, plus, it may kake it a bit easier. you should also consider buying a piece of pipe that has the OD the same as the ID of the cat. cram that pipe into the cat to give it a smooth airflor through the cat to prevent turbulance inside the gutted cat. wear a mask, im not a genius, but i dont think breathing the cat guts is a good thing.

The Dingo

:iagree: From my understanding, breathing that stuff in is FAR from being good for you...

Phobos84

The insides of a cat are made up of impure platinum and bromine. Non-toxic but berathing in dust is never very good for you.

CorvetteZ51Racer

You can't gut the precats, only remove them from the system. And honestly, if you drive the car hard, don't worry about getting every little piece of debris out of the cat. If it's broken loose and you can't get it out past the AIR injection tube in the cat, it will blow itself out...even through mufflers....don't ask me how I know :D

86VetteBill

OK - last question, I think. I haven't looked at the cat very closely, but I'm assuming that the best (and only way?) is to gut it from the back side or front side. There's no underside holes like on the 70's cats?

Unless I'm told otherwise, I'm planning on poking from the rear :eek: and then running the motor to blow out all of the pieces.

Or since I can't get in there with my hand, do I poke while the motor is running, using a dust mask, letting it come out a little at a time? :confused:

I'm probably planning this to death!! Just do it! :D

BIG JIM 54

Well....

I have one question. WHY? Is concern for the air you breathe not important? Hey. I'm one to make my vette louder, faster, lighter but never dirtier.

I've read on other topic here where a member lost 35 HP by removing the resonators from the back. What do you think removing the cats from a street driven car will do to a computer controlled Corvette. And what do you think doing that will do to your cars ability to pass emissions laws and inspections? If your state doesn't have any emissions inspections like we here in CA have to endure, it's just a matter of time.

Clean air is everyone's responsibilty. OK, I'll quit hugging my tree now.

BIG JIM

Phobos84

As far as the computer it will do nothing. in a 1986 Vette with the factory OBD 1 system it will not send any code or have any problems. As far as emissions testing the laws are slowly getting softer and softer because of our dumb butt of a president. (sorry don't want to start a debate) I can't speek for everyone but I know I only drive my vette arround 9000 miles a year. Thats about it. As apposed to my 98 Blazer that is my daily driver. The extra pollution that my car produces dosn't amount to anything. If you really want to help pollution in cars put cats and AIR pumps on race cars. Everything from NASCAR to speed boats. That will do a lot more good then me having one. If your car is a daily driver and you put a lot of miles on it then sure if you want put a cat on it but for the rest of us whats the point?

Rays91L98

:confused:
why can't you gut the pre cats?

BIG JIM 54

I was just playing Devil's Advocate a bit. But it is illegal to remove or gut the cats. In CA, we can't register our cars unless they pass the dreaded "smog test" which is both visual and sniffer approved. And there's no appeal and no recourse.
Nothing has been "relaxed" in CA, I can say that. Each state pretty much regulates their own air managment board. We have the CARB. I didn't mean any distain from me about what you do to your car. I didn't mean it that way. But without my main cat, I couldn't run the straight pipes out the back. It would be too loud then so your going to get restriction anyway from something, either cats or mufflers. FWIW.

As a side note, I agree with your assestment of our Preznit. And I'm a Republican!

BIG JIM


[Modified by BIG JIM 54, 11:10 AM 1/13/2003]

DaveD

I gutted my precats because the honeycomb in them broke loose and rattled around. I cut the pipes off the front of the precats right in the middle of the weld where they were originally welded on. Before cutting each pipe off though I drilled four small (1/16) holes, two on the pipe, 180 degrees apart and two on the cat, 180 degrees apart, right next to where I was cutting. these became the index marks for welding the pipe (s) back on in the same orientation. Took the pipes up the street to the local welder, explained the indexing to him, and $40 later walked out with a Y pipe that looked like the original. It was welded over the original weld and the weld also filled in the indexing holes. Worked great. Better than a $200+ new one. :)

Phobos84

As a side note, I agree with your assestment of our Preznit. And I'm a Republican!

BIG JIM

even though I'm a democrat I find that most people can agree on something.

Didn't mean to make it sound like I was yelling at you or anything. In my area we don't have smog testing but we do have it in the larger citys. We however do have visual inspections. My mecanic told me that if I wanted to remove the cat to gut it and put it back on. The law says you have to have a cat. It dosen't say there has to be anything in it. :yesnod: