Fixing exhaust - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cliffsta · 12-02-2004, 05:46 PM

Hoookay. My exhaust is in, pitiful, disgusting, shape. The muffler has holes in it and is clogged, and the cat is clogged. The back pressure is so bad you can here the motor miss, then the pressure get released and it keeps going. not like a stumble, you just here a miniscule jump. And it sounds like i got ghetto exhaust on it with the clogged cat and the rot in the muffler. So is it worth it to go to the exhaust shop and have them install a new muffler, and probably pipes? Or should i just scrounge for some pipes and buy a muffler and do it myself? I may or may not get access to a welder, if that matters.
Also, has anyone "modified" their cat, by cutting it off, welding in a piece of pipe, and welding the cat shell back over it? AND, isn't there a time period, like 25 or 30 years were you don't have to pass emissions, like having a cat?
I know its a lot of ????s but I'm really curious.

SanitysBane · 12-02-2004, 07:13 PM

on the cat thing, usally u just get a pipe or something like that and beat all the crap out of it till its empty and put it back on, really easy that way, and the emitions stuff depends were you live. with the headers i have on the truck building an exhaust set up wasn't hard at all, jsut straight pipes minus 2 turn downs welded together to make a jump over the tranny member,

rolson1039 · 12-02-2004, 07:39 PM

getting a cat at the midas shop is an expensive proposition id prolly hollow it out as long as noone is going to check it on ya then id get the walker pipes at the auto parts store and the cheapo muffler the whole thing costs about $100 and do it myself make sure ya have the dremel and sawsall handy to cut where needed make it easy

cliffsta · 12-02-2004, 08:52 PM

I heard hollowing it out created back pressure, too. That true? That's why asked about welding in a piece of straight pipe through it.

kevinr1970 · 12-02-2004, 09:36 PM

Don't know about emmisions where your at, but in WA, I think this the last year for 1982, next year is the last year for 1983 and so on.
Have you taken your truck through the inspection since you bought it? Do you know if it will have to be inspected in the following year?
I was just looking at a JEG's catalog and no cat exhaust systems with all hardware that are "bolt-on" are just around $100. A cat back system is a little more, but includes mufflers.
Just thought.

SanitysBane · 12-02-2004, 09:53 PM

having an empty shell on there won't create any back presure

78chevstepside · 12-02-2004, 10:23 PM

washington state goes back 25 years. after 25 years the car or truck becomes exempt. I have finally reached that barrier . In washington they dont do visual just a snorkle test. I removed every bit of the smog stuff on my 78 many moons ago( before they had testing) and still got through. . snorkle tests are easier to get through imo. If that was the case I would remove the cat

cliffsta · 12-02-2004, 11:47 PM

It's really not a matter of inspection, as i know a few, places, that you can walk in, pay $10 bucks, and they slap on a sticker. Literrallly, they give ANYTHING a sticker. So i guess i could eliminate the cat. We don't do actual snorkle tests or anything either. I never see any Louisiana members, so i'll just ask around here when we become fully "emission exempt".
kevinr - yeah i saw them, dual exhaust for like 100 bucks. If i had a 100 bucks, or better yet, if i wasn't taking my Xmas money and getting a carb, i would get the exhaust.
So in you guys' opionion, do it myself? I can already here my old man B----ng "bah its all rusted you'll never get that done". 5 minutes later, he'll be out there doing it with me....

Mike76251 · 12-03-2004, 06:28 AM

I put my system in myself,
It is not that hard to do.

The biggest problem was getting over the trans hump.

I think you will need a welder to do it though......I used a stick machine.

79gmcc15 · 12-03-2004, 08:23 AM

I took out all the pipe from just past the T for the stock system and use pipe clamps and clamped on a flowtech Raptor muffler*$20* on * http://www.holley.com/HiOctn/ProdLin...FT/Raptor.html *. the muffler is right under my butt, then origonaly I had about 2 feet of pipe with turn down to dump it right by the tire. and used pipe clamps all the way. got pipe mostly from pepboys. sounded pretty good. got a good low rumble at idle and the faster you went the quiter it got. but now I took off about 18" so its now actualy quiter. whole thing cost me about $50 and that was winging it. if I planed it out, woulda cost me alot less lol. just my 2 cents matt

jimfulco · 12-04-2004, 02:49 AM

I believe La. goes back to 1980 on trucks for a cat-check, but most won't get on their knees to check for it around here. Got the old pellet-type cat? The one with the flat bottom with a plug in it? Remove the plug & tap the cat with a mallet or a chunk of wood until all the little beads come out into a trash bag (they can leave black marks on concrete). Crank the engine to blow out the rest of them. (Some folks just pull the plug & drive around with it out for a while

) Plug the hole back (I used a freeze plug, 1-5/8" I think).

cliffsta · 12-11-2004, 06:44 PM

so the cat is before the muffler? Its that flat rectangle thing under the cab with the indent for a plug? I JUST crawled up under there. I'm a little ignorant about exhaust.

Mike76251 · 12-12-2004, 04:58 AM

That's probably it..............not that I would know.
I had a piece of pipe there before I put the duals on......"factory" equipped!

jimfulco · 12-13-2004, 03:05 AM

Yes, between the Y and the muffler.

12-02-2004, 05:46 PM	#1
cliffsta Stepsides RULE Join Date: Jul 2004 Location: Pineville, LA Posts: 1,921	Fixing exhaust Hoookay. My exhaust is in, pitiful, disgusting, shape. The muffler has holes in it and is clogged, and the cat is clogged. The back pressure is so bad you can here the motor miss, then the pressure get released and it keeps going. not like a stumble, you just here a miniscule jump. And it sounds like i got ghetto exhaust on it with the clogged cat and the rot in the muffler. So is it worth it to go to the exhaust shop and have them install a new muffler, and probably pipes? Or should i just scrounge for some pipes and buy a muffler and do it myself? I may or may not get access to a welder, if that matters. Also, has anyone "modified" their cat, by cutting it off, welding in a piece of pipe, and welding the cat shell back over it? AND, isn't there a time period, like 25 or 30 years were you don't have to pass emissions, like having a cat? I know its a lot of ????s but I'm really curious. __________________ 1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord

12-02-2004, 07:13 PM	#2
SanitysBane Registered User Join Date: May 2004 Location: Lubbock, Texas Posts: 2,121	on the cat thing, usally u just get a pipe or something like that and beat all the crap out of it till its empty and put it back on, really easy that way, and the emitions stuff depends were you live. with the headers i have on the truck building an exhaust set up wasn't hard at all, jsut straight pipes minus 2 turn downs welded together to make a jump over the tranny member, __________________ '96 Nissan Pathfinder '02 Firebird Trans Am. '88 K5 Blazer

12-02-2004, 07:39 PM	#3
rolson1039 Registered User Join Date: Oct 2002 Location: NJ Posts: 404	getting a cat at the midas shop is an expensive proposition id prolly hollow it out as long as noone is going to check it on ya then id get the walker pipes at the auto parts store and the cheapo muffler the whole thing costs about $100 and do it myself make sure ya have the dremel and sawsall handy to cut where needed make it easy __________________ so many trucks so little time!!!

12-02-2004, 08:52 PM	#4
cliffsta Stepsides RULE Join Date: Jul 2004 Location: Pineville, LA Posts: 1,921	I heard hollowing it out created back pressure, too. That true? That's why asked about welding in a piece of straight pipe through it. __________________ 1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord

12-02-2004, 09:36 PM	#5
kevinr1970 Senior Member Join Date: Aug 2004 Location: Everett, WA Posts: 2,316	Don't know about emmisions where your at, but in WA, I think this the last year for 1982, next year is the last year for 1983 and so on. Have you taken your truck through the inspection since you bought it? Do you know if it will have to be inspected in the following year? I was just looking at a JEG's catalog and no cat exhaust systems with all hardware that are "bolt-on" are just around $100. A cat back system is a little more, but includes mufflers. Just thought. __________________ 2009 Honda Fit CfC (bsf 44.9 mpg) 2000 Tahoe Limited 1991 GMC CrewCab Dually 2wd, will end up swb, not dually and replace CCswb below 1991 GMC CrewCab Dually 4x4, just going to fix things up for now 1982/1989 K5/GMC Jimmy 2wd 1987 GMC 1/2 ton swb 2wd Crew (sold)

12-02-2004, 09:53 PM	#6
SanitysBane Registered User Join Date: May 2004 Location: Lubbock, Texas Posts: 2,121	having an empty shell on there won't create any back presure __________________ '96 Nissan Pathfinder '02 Firebird Trans Am. '88 K5 Blazer

12-02-2004, 10:23 PM	#7
78chevstepside Registered User Join Date: Nov 2002 Location: lacenter, washington Posts: 718	washington state goes back 25 years. after 25 years the car or truck becomes exempt. I have finally reached that barrier . In washington they dont do visual just a snorkle test. I removed every bit of the smog stuff on my 78 many moons ago( before they had testing) and still got through. . snorkle tests are easier to get through imo. If that was the case I would remove the cat

12-02-2004, 11:47 PM	#8
cliffsta Stepsides RULE Join Date: Jul 2004 Location: Pineville, LA Posts: 1,921	It's really not a matter of inspection, as i know a few, places, that you can walk in, pay $10 bucks, and they slap on a sticker. Literrallly, they give ANYTHING a sticker. So i guess i could eliminate the cat. We don't do actual snorkle tests or anything either. I never see any Louisiana members, so i'll just ask around here when we become fully "emission exempt". kevinr - yeah i saw them, dual exhaust for like 100 bucks. If i had a 100 bucks, or better yet, if i wasn't taking my Xmas money and getting a carb, i would get the exhaust. So in you guys' opionion, do it myself? I can already here my old man B----ng "bah its all rusted you'll never get that done". 5 minutes later, he'll be out there doing it with me.... __________________ 1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord

12-03-2004, 06:28 AM	#9
Mike76251 Senior Member Join Date: Mar 2003 Posts: 2,499	I put my system in myself, It is not that hard to do. The biggest problem was getting over the trans hump. I think you will need a welder to do it though......I used a stick machine.

12-03-2004, 08:23 AM	#10
79gmcc15 Gettin It One Pice At A Time Join Date: Oct 2004 Location: everett, washington Posts: 2,688	I took out all the pipe from just past the T for the stock system and use pipe clamps and clamped on a flowtech Raptor muffler$20 on * http://www.holley.com/HiOctn/ProdLin...FT/Raptor.html . the muffler is right under my butt, then origonaly I had about 2 feet of pipe with turn down to dump it right by the tire. and used pipe clamps all the way. got pipe mostly from pepboys. sounded pretty good. got a good low rumble at idle and the faster you went the quiter it got. but now I took off about 18" so its now actualy quiter. whole thing cost me about $50 and that was winging it. if I planed it out, woulda cost me alot less lol. just my 2 cents matt __________________ RIP ELJAY Work In Progress 1979 GMC C1500 Trailering Special. Getting the truck done, one piece at a time. “You can tell a lot about a fellow’s character by his way of eating jellybeans.”Ronald Reagan “I don’t know the key to success but I know the key to failure is trying to please everybody.” Bill Cosby Last edited by 79gmcc15; 12-03-2004 at 08:27 AM.*

12-04-2004, 02:49 AM	#11
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	I believe La. goes back to 1980 on trucks for a cat-check, but most won't get on their knees to check for it around here. Got the old pellet-type cat? The one with the flat bottom with a plug in it? Remove the plug & tap the cat with a mallet or a chunk of wood until all the little beads come out into a trash bag (they can leave black marks on concrete). Crank the engine to blow out the rest of them. (Some folks just pull the plug & drive around with it out for a while) Plug the hole back (I used a freeze plug, 1-5/8" I think).

12-11-2004, 06:44 PM	#12
cliffsta Stepsides RULE Join Date: Jul 2004 Location: Pineville, LA Posts: 1,921	so the cat is before the muffler? Its that flat rectangle thing under the cab with the indent for a plug? I JUST crawled up under there. I'm a little ignorant about exhaust. __________________ 1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord

12-12-2004, 04:58 AM	#13
Mike76251 Senior Member Join Date: Mar 2003 Posts: 2,499	That's probably it..............not that I would know. I had a piece of pipe there before I put the duals on......"factory" equipped!

12-13-2004, 03:05 AM	#14
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	Yes, between the Y and the muffler.



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