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#1 |
Registered User
![]() Join Date: Feb 2005
Location: Northeast--Bethlehem, Pennslyvania
Posts: 642
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cat on my 1979
Just got my truck inspected, The garage guy said I should have cats on my exhaust. How can I tell if my truck needs them. When I got this truck it had none. I know over the years people took them off. Maybe that is what happened to mine. He still inspected the truck because the mileage was under 5000 miles since last inspection. Any help, Thanks, John
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Big Blue ( John ) 79 Chevy Pick up.....My Dailey STILL Working on a frame up: 1987 Truck body on a 78 Blazer frame. Need cab blasted to start project. Got the cab BLASTED, Now Prep and Paint. Started to lay SOME BONDO and primer. Done, Ordering paint. Got paint, Stuff painted,Cab,Fenders, Hood more later. 9/7/2015 Got the clear coat on,now time to take one off. Started to put things back (What a nightmare) like the heating and AC stuff,inside wire harness, outside AC unit and booster, still more. May 2016, still working on the inside. Got duck work in,heating and AC. Radio (stock) in dash with after market in console later, Speaker are hooked up, Steering column is in. Getting ready to drop the cab onto the frame, Working on engine now since I have the room. Well here it is 2018, got the engine in and it runs, now I need to get the exhaust system in so I can adjust the lifters, to loud right now. Got the exhaust on now I am waiting for the break parts to come in. |
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#2 |
driving is in my blood
Join Date: Dec 1999
Location: Mesa AZ
Posts: 5,720
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Re: cat on my 1979
Call GM parts department and give them your vin. Thats all it takes.
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-78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me. |
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#3 |
Registered User
Join Date: Oct 2015
Location: Waskatenau, Alberta
Posts: 259
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Re: cat on my 1979
Not positive about American trucks, but by 79 all of the Canadian trucks I have seen came with cats. I believe there were a few exceptions.... 1 tons , and heavy 3/4 tons.
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#4 |
Registered User
Join Date: Oct 2014
Location: Tell City, IN
Posts: 637
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Re: cat on my 1979
It depends on the trucks GVWR.
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Big Nate Carp. Local 224. Buy made in the USA! 03 F350 6.0 Daily Race Truck. 79 C70 366 Project Dump. |
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#5 |
Registered User
![]() Join Date: Sep 2015
Location: Sioux Falls, South Dakota
Posts: 702
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Re: cat on my 1979
GMs VIN based cataloging started in 1990 calling a parts department won't help
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"Orange Crush" |
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#6 |
Registered User
Join Date: Feb 2005
Location: Saskatoon, SK
Posts: 97
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Re: cat on my 1979
I have a low km untouched Canadian '79 and I'm pretty confident it never had a cat. It is a heavy half though so that may have something to do with it.
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#7 |
Master Hater
Join Date: Apr 2006
Location: Temple,Tx.
Posts: 402
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Re: cat on my 1979
in the US I know up to 86 if its under 8,599gvwr it needs a cat, 8600 and above did not have a cat. My 86 C6P 3/4 didn't have one because it was rated 8600 GVWR.Also you should have a sticker on the rad support that will tell you what pollution control devices it had, Air,egr, catalist ect.
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1997 C1500 ECSB 4.3/NV3500 8.5 3.42 "This evening, all of you bleeding hearts... why don't just go ahead and hug yourself for the next 20 minutes or so, because there's a really good chance you're gonna be offended".- Captain Owen Honors |
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#8 |
Registered User
![]() Join Date: Feb 2005
Location: Northeast--Bethlehem, Pennslyvania
Posts: 642
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Re: cat on my 1979
Thanks everyone, sure is a lot to know. Since he inspected the truck do I really need one?
John
__________________
Big Blue ( John ) 79 Chevy Pick up.....My Dailey STILL Working on a frame up: 1987 Truck body on a 78 Blazer frame. Need cab blasted to start project. Got the cab BLASTED, Now Prep and Paint. Started to lay SOME BONDO and primer. Done, Ordering paint. Got paint, Stuff painted,Cab,Fenders, Hood more later. 9/7/2015 Got the clear coat on,now time to take one off. Started to put things back (What a nightmare) like the heating and AC stuff,inside wire harness, outside AC unit and booster, still more. May 2016, still working on the inside. Got duck work in,heating and AC. Radio (stock) in dash with after market in console later, Speaker are hooked up, Steering column is in. Getting ready to drop the cab onto the frame, Working on engine now since I have the room. Well here it is 2018, got the engine in and it runs, now I need to get the exhaust system in so I can adjust the lifters, to loud right now. Got the exhaust on now I am waiting for the break parts to come in. |
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#9 |
Registered User
Join Date: Mar 2013
Location: Campbellsville, KY
Posts: 888
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Re: cat on my 1979
If it's legal the only reason you "need" one is if it's a nuts-and-bolts restoration and you're worried about what's "original" to a fault. Otherwise, especially on a carbureted truck, there's no benefit to it. I'm not as familiar with emissions equipment in the 70's, but as ironroad9c1 said, trucks 8,600 GVW and over (which was most decently-optioned 3/4 tons and nearly all, if not all, 1-tons) didn't have to have cats in the mid 80's. From what I've observed most, if not all, states only require such emissions equipment as came on a particular vehicle from the factory.
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Alex V. ------ 1967 C10 Suburban, 350/NP435, Green/Green, PS, PB, HD cooling, charging, shocks, and springs. 1985 GMC C3500 SRW, Sierra Classic, 454/TH400, white/blue. |
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#10 |
Registered User
Join Date: Oct 2009
Location: .
Posts: 2,185
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Re: cat on my 1979
If you plan to drive less than 5k a year, I'd leave them off. I have my pa emissions insp license and am in the same emission tier as you.
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#11 |
driving is in my blood
Join Date: Dec 1999
Location: Mesa AZ
Posts: 5,720
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Re: cat on my 1979
A quality high flow cat certainly won't hinder flow at all so if you need them then put em on it won't hurt anything. My 79 1/2ton 2wd required them. My 78 1/2ton 2wd does not.
__________________
-78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me. |
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#12 |
Registered User
Join Date: May 2009
Location: Motor City
Posts: 9,194
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Re: cat on my 1979
I'm surprised to hear that.
Our '75 swb 1/2 ton 2wd had a cat on it. It blew the bottom out and scattered the little pellets all over the highway. K
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Chevrolet Flint Assembly 1979-1986 GM Full Size Truck Engineering 1986 - 2019 Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926 My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524 Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/ |
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#13 |
Registered User
Join Date: Apr 2016
Location: Albany Oregon
Posts: 34
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Re: cat on my 1979
I spent a decade in the exhaust business. Yours was a common question. Everyone (mostly) has steered you in the right direction.
The 2 most common and simple ways to tell is look for the emissions sticker, it will say "catalyst" or "non-catalyst" on it USUALLY. The other simple way is to look under the truck. If there is a large (possibly wide oval shaped) heat shield above the exhaust around the rear of cab to front of bed area it likely had one. IF the exhaust is original, look about 3 feet back from the manifold to see if there's a newer section of pipe around 2 feet long. That would indicate a "sub-pipe". But as said, most 3/4 tons and up didn't have one. And as mentioned, the newer hi-flow cats don't really hinder performance, especially when installed as a pair on dual exhaust. Spendy, but looks nice and balances sound as well. |
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