Witch yr did CATS Start? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

82GMCSWB · 06-12-2002, 08:13 PM

Hey, I have a 1982 GMC SWB Serria Classic, it used to be a desial, anyhow, did it come stock with CATS on it? (Catallatic Converters) cause a friend is saying no, but yet it has them on it... hmmm

thanks
Matt

*Zkast* · 06-13-2002, 12:09 AM

Most everything of GM's started using cats back in '74 and all (I believe) had them by '77-'78. I'm not real sure about deisel engines though.. they may have been excluded.

P.S. if you looking to get by without them? most states mandate you must have cats on vehicles 78 and up.

bradshop · 06-13-2002, 05:41 AM

Well not over running the last reply but my 85 chevy c-30 did not come stock with cats. Although it did come with two stock smog pumps.

gchemist · 06-13-2002, 07:06 AM

Diesel trucks did not have cats until the late 80's. Your '82 should not have them on. Someone must have added them for some reason. Probably got ripped off by a muffler shop!!

By making it a gasoline engine some states require that the cats be put on. If you keep the truck registered as a diesel then it may not need them. If a newer year model engine is put in then the emmission stuff of the new engine model must be on it in some states. California is a good example.

82GMCSWB · 06-13-2002, 12:43 PM

well, I am confused, I am also thinking I shouldn't have them, but I don't wanna run the risk... who would I contact locally to find this out? maybe the local GMC Dealership? maybe they could tell me? I mihgt just keep them anyhow, but it would be nice to know, so maybe one day down the road, I could cut them off till then, there not really hampering anything...

1974ChevyC10 · 06-13-2002, 02:42 PM

before 1975 vehicles didnt come with catalytic convertors.after 1975 they were added but the vehicle manufacturers came up with ways around them.i have a 74 pickup that doesnt have them.my first truck was a 78 chevy that didnt have cats and it was a 1/2 ton.in fact every truck ive ever owned didnt have cats.as far as diesels they to the best of my knowledge were exempt from cats as well.

*Zkast* · 06-13-2002, 11:11 PM

Contact your states Dept' Of Transportation. If you have a state inspection you can call a inspection station and ask if that model/year should have them. After all... they are the folks who will give you grief if there is a problem. Guess its better to find out from them....

79BIG10 · 06-14-2002, 01:54 AM

My 79 had a cat on it originally. Even with a Big 10 rating as well.

**Desert Rat** · 06-17-2002, 02:14 PM

My 79 Blazer had a cat there behind the 350,muffler shop said they could make exhaust system in 2.5" like i want bent and ready to bolt up,but technically they cant install it on cat vehicles,so ill come home and bolt it up,theyll hang it all and do clamps so its ready but they cant leave it there.$250 should make that 402 sound good

82GMCSWB · 06-19-2002, 02:38 PM

well, I brought my truck in today, I am having it all redone, it will have the Headman Elite Series Headers, with 2.50 pipe strait out two dual 40 Series FlowMasters, the Muffler guy called and asked for me and said it would be ok to take em off sence it was desial, and he ran some tests and talked with ppl, and found out I really didn't need them, so there being chopped off, and when it comes time to take the test for admissions and if they say "wait u need them" I'll say ok, and put my brand new ones on, till then it's all ok

SCOTI · 06-28-2002, 07:08 PM

Another thing to consider is that you can't ' LEGALLY ' install cats in any other configuration than what was available from the factory. So that means ' LEGALLY ' you can't have more than 1 cat on the truck or it's not technically legal even though it would still burn as clean or cleaner than w/one single cat(unless w/an engine swap). I researched this & came to the conclusion that it wasn't worth the extra $$ to run 2 cats because technically it is as illegal as no cats so why spend the extra $. After testing my 78 camino w/original 305 + brand new hi-flow single cat into duals w/dumps(it passed) & then retesting w/new 355 w/L-82 spec drivetrain/4-barrel, 3/4 length headers & no cats w/true 2.5 dual exhaust it actually ran much cleaner when it passed the sniffer test. So even though the newer tighter engine was more smog friendly it was still not legal unless it only had 1 cat.

Longhorn Man · 06-30-2002, 12:04 PM

In addition to the number of cats, location is a problem too.
Rat, why did they tell you they couldn't do it? Did they say? Federal law says that anything after the cat is fair game. The onlything governing the rear 1/2 of the exhaust is sound level, and exit location.
As for finding out about your exhaust, I would contact your local inspection station. Short of that, i would hack them off. Even Cali has diesel vehicles exempt.
The manufacturers were adding catilitic converters before they were required to do it. They were doing this for the engine manigment systems.
Interestingly enough, the new deisels have verters on them now too. Some do anyways.

Grim Reaper · 07-29-2002, 03:02 PM

Well if it use to be a diesel the VIN still say's it is. Unless you have to do safety inspection how will they ever know it was converted to Gas?

Check your Registartion and see if it shows Gas or Deisel.
To answer your question about Cats: 78 was the first year most 1/2 tons got cats. Cali models were the exception, they started either 74 or 76. I think it was 76.
CARS started in 74 pretty much accross the board.
1 Tons were early 80's There was a GWVR exculsuion that let them go to that point.

78SilveradoSWB · 08-05-2002, 10:29 PM

Cats started during the latter half of the 78 model year for 1/2 ton trucks according to my GM shop manual. My truck was manufactured during the early 78 model year and does not have the CATs. Noted related change was the gas gauge stating must use unleaded fuel and the gas doors were used in conjunction with the change.

jimss420 · 09-01-2002, 03:55 PM

Alright, i live in CA and have done extensive reasearch about smog equipment, since i had to register my truck which is a 79' body with a 78' and at the time had an 83' 305, and it was a nightmare. What i know is i have a 78' 1/2 ton Big 10, 6400
GVWR. with a 350 with an edelbrock 1400, 600cfm electric choke carb, pcv valve, thermostatic air cleaner, efe valve, fuel evap, 3inch high flow single exuast, and an egr valve, and it passes the CA emmision test. If you have a smog pump on your truck you can take it off and put on the regular exaust manifolds and rip the emission label off the core support and tell them its a federal 49 state veh, even in CA, you can get away with some stuff. Now i've seen 2 cats put put on truck by muffler shops, and about half the smog guys will let it pass and the other wont, they only let it pass because the 97 chevy truck came with dual cats into the muffler. Now 3/4 2wd i believe have cats but the 4x4 3/4 and i think does and anything bigger doesnt either, i think the cut off is 7000 GVWR. now about the diesel thing, my cousin has a 83 suburban 3/4 ton with a 6.2 diesel, 4x4, it doesnt have a cat, and it doenst ever have to be smogged. However, he put in a seriously built 454 and its loud too, technically he doesnt have to smog it cause the DMV thinks its a diesel, but if the Highway Patrol pulls him over and inspects it he could get some serious fines. And i've heard of the CHP doing that out here in CA and busting people for taking off smog equipment or not having the right equip on it. Even had a buddy with a 71 nova, which is exempt from smog get in trouble, and the gave him a ticket for no pcv valve and no thermo air cleaner. They are jerks out here in CA.

06-12-2002, 08:13 PM	#1
82GMCSWB Registered User Join Date: Jun 2002 Posts: 8	Witch yr did CATS Start? Hey, I have a 1982 GMC SWB Serria Classic, it used to be a desial, anyhow, did it come stock with CATS on it? (Catallatic Converters) cause a friend is saying no, but yet it has them on it... hmmm thanks Matt __________________ -=Current Projects=- 1982 GMC SWB Serria Classic -=Current Photo's=- Front View Side View UPDATES SOON

06-13-2002, 07:06 AM	#4
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	Diesel trucks did not have cats until the late 80's. Your '82 should not have them on. Someone must have added them for some reason. Probably got ripped off by a muffler shop!! By making it a gasoline engine some states require that the cats be put on. If you keep the truck registered as a diesel then it may not need them. If a newer year model engine is put in then the emmission stuff of the new engine model must be on it in some states. California is a good example. __________________ Gerardo a.k.a. Mad Chemist Silverado XST videos

06-13-2002, 12:43 PM	#5
82GMCSWB Registered User Join Date: Jun 2002 Posts: 8	well, I am confused, I am also thinking I shouldn't have them, but I don't wanna run the risk... who would I contact locally to find this out? maybe the local GMC Dealership? maybe they could tell me? I mihgt just keep them anyhow, but it would be nice to know, so maybe one day down the road, I could cut them off till then, there not really hampering anything... __________________ -=Current Projects=- 1982 GMC SWB Serria Classic -=Current Photo's=- Front View Side View UPDATES SOON

06-13-2002, 02:42 PM	#6
1974ChevyC10 Overworked and Underlaid Join Date: May 2002 Location: Flagstaff,Arizona Posts: 1,279	before 1975 vehicles didnt come with catalytic convertors.after 1975 they were added but the vehicle manufacturers came up with ways around them.i have a 74 pickup that doesnt have them.my first truck was a 78 chevy that didnt have cats and it was a 1/2 ton.in fact every truck ive ever owned didnt have cats.as far as diesels they to the best of my knowledge were exempt from cats as well. __________________ I'd rather push a Chevy than drive a Ford The Beast-1978 C10 LWB Red-1978 C10 LWB (Uncle Mike)Michael Henry Millett 11/5/1957 to 03/08/2012 Gone but will never be forgotten-RIP (Uncle Chuck)Charles Manning Gulbronsen Sr 1956-2012 Taken from us to soon but you will live on in our hearts-RIP

06-14-2002, 01:54 AM	#8
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,775	My 79 had a cat on it originally. Even with a Big 10 rating as well. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson

06-13-2002, 12:09 AM	#2
Zkast Account Suspended Join Date: May 2002 Location: Olathe, Kansas Posts: 929	Most everything of GM's started using cats back in '74 and all (I believe) had them by '77-'78. I'm not real sure about deisel engines though.. they may have been excluded. P.S. if you looking to get by without them? most states mandate you must have cats on vehicles 78 and up.

06-13-2002, 05:41 AM	#3
bradshop Registered User Join Date: May 2002 Location: Reidsville, NC USA Posts: 19	Well not over running the last reply but my 85 chevy c-30 did not come stock with cats. Although it did come with two stock smog pumps.

06-13-2002, 11:11 PM	#7
Zkast Account Suspended Join Date: May 2002 Location: Olathe, Kansas Posts: 929	Contact your states Dept' Of Transportation. If you have a state inspection you can call a inspection station and ask if that model/year should have them. After all... they are the folks who will give you grief if there is a problem. Guess its better to find out from them....

06-17-2002, 02:14 PM	#9
Desert Rat Senior Member Join Date: Dec 1999 Location: Darrington, Washington Posts: 3,963	My 79 Blazer had a cat there behind the 350,muffler shop said they could make exhaust system in 2.5" like i want bent and ready to bolt up,but technically they cant install it on cat vehicles,so ill come home and bolt it up,theyll hang it all and do clamps so its ready but they cant leave it there.$250 should make that 402 sound good

06-19-2002, 02:38 PM	#10
82GMCSWB Registered User Join Date: Jun 2002 Posts: 8	well, I brought my truck in today, I am having it all redone, it will have the Headman Elite Series Headers, with 2.50 pipe strait out two dual 40 Series FlowMasters, the Muffler guy called and asked for me and said it would be ok to take em off sence it was desial, and he ran some tests and talked with ppl, and found out I really didn't need them, so there being chopped off, and when it comes time to take the test for admissions and if they say "wait u need them" I'll say ok, and put my brand new ones on, till then it's all ok __________________ -=Current Projects=- 1982 GMC SWB Serria Classic -=Current Photo's=- Front View Side View UPDATES SOON

06-28-2002, 07:08 PM	#11
SCOTI Registered User Join Date: Apr 2001 Location: DALLAS,TX Posts: 21,938	Another thing to consider is that you can't ' LEGALLY ' install cats in any other configuration than what was available from the factory. So that means ' LEGALLY ' you can't have more than 1 cat on the truck or it's not technically legal even though it would still burn as clean or cleaner than w/one single cat(unless w/an engine swap). I researched this & came to the conclusion that it wasn't worth the extra $$ to run 2 cats because technically it is as illegal as no cats so why spend the extra $. After testing my 78 camino w/original 305 + brand new hi-flow single cat into duals w/dumps(it passed) & then retesting w/new 355 w/L-82 spec drivetrain/4-barrel, 3/4 length headers & no cats w/true 2.5 dual exhaust it actually ran much cleaner when it passed the sniffer test. So even though the newer tighter engine was more smog friendly it was still not legal unless it only had 1 cat. __________________ 67SWB-B.B.RetroRod 64SWB-Recycle 89CCDually-Driver/Tow Truck 99CCSWB Driver All Fleetsides @rattlecankustoms in IG Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive. It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar..... *Cubic inches is like Indiana Jones with a cheap pistol.*

06-30-2002, 12:04 PM	#12
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	In addition to the number of cats, location is a problem too. Rat, why did they tell you they couldn't do it? Did they say? Federal law says that anything after the cat is fair game. The onlything governing the rear 1/2 of the exhaust is sound level, and exit location. As for finding out about your exhaust, I would contact your local inspection station. Short of that, i would hack them off. Even Cali has diesel vehicles exempt. The manufacturers were adding catilitic converters before they were required to do it. They were doing this for the engine manigment systems. Interestingly enough, the new deisels have verters on them now too. Some do anyways.

07-29-2002, 03:02 PM	#13
Grim Reaper Registered User Join Date: Jul 2001 Location: Atlanta GA Posts: 1,704	Well if it use to be a diesel the VIN still say's it is. Unless you have to do safety inspection how will they ever know it was converted to Gas? Check your Registartion and see if it shows Gas or Deisel. To answer your question about Cats: 78 was the first year most 1/2 tons got cats. Cali models were the exception, they started either 74 or 76. I think it was 76. CARS started in 74 pretty much accross the board. 1 Tons were early 80's There was a GWVR exculsuion that let them go to that point. __________________ Grim-Reaper 70 Pontiac LeMans Sport Convertible, worlds longest resto in progress Looking for 71-72 2wd Blazer or Jimmy Project

08-05-2002, 10:29 PM	#14
78SilveradoSWB Senior Member Join Date: Apr 2002 Location: Beaverton, OR Posts: 1,615	Cats started during the latter half of the 78 model year for 1/2 ton trucks according to my GM shop manual. My truck was manufactured during the early 78 model year and does not have the CATs. Noted related change was the gas gauge stating must use unleaded fuel and the gas doors were used in conjunction with the change.

09-01-2002, 03:55 PM	#15
jimss420 Registered User Join Date: Aug 2002 Posts: 4	Alright, i live in CA and have done extensive reasearch about smog equipment, since i had to register my truck which is a 79' body with a 78' and at the time had an 83' 305, and it was a nightmare. What i know is i have a 78' 1/2 ton Big 10, 6400 GVWR. with a 350 with an edelbrock 1400, 600cfm electric choke carb, pcv valve, thermostatic air cleaner, efe valve, fuel evap, 3inch high flow single exuast, and an egr valve, and it passes the CA emmision test. If you have a smog pump on your truck you can take it off and put on the regular exaust manifolds and rip the emission label off the core support and tell them its a federal 49 state veh, even in CA, you can get away with some stuff. Now i've seen 2 cats put put on truck by muffler shops, and about half the smog guys will let it pass and the other wont, they only let it pass because the 97 chevy truck came with dual cats into the muffler. Now 3/4 2wd i believe have cats but the 4x4 3/4 and i think does and anything bigger doesnt either, i think the cut off is 7000 GVWR. now about the diesel thing, my cousin has a 83 suburban 3/4 ton with a 6.2 diesel, 4x4, it doesnt have a cat, and it doenst ever have to be smogged. However, he put in a seriously built 454 and its loud too, technically he doesnt have to smog it cause the DMV thinks its a diesel, but if the Highway Patrol pulls him over and inspects it he could get some serious fines. And i've heard of the CHP doing that out here in CA and busting people for taking off smog equipment or not having the right equip on it. Even had a buddy with a 71 nova, which is exempt from smog get in trouble, and the gave him a ticket for no pcv valve and no thermo air cleaner. They are jerks out here in CA.



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