Missing Factory Emissions Equipment?

[savatreatabvr]

I'm getting ready to take my 1973 C20 454 through emissions here in Arizona but I don't have any smog equipment, no EGR, no CATs no PUMP, nothing. The truck originally came with a 350 so I'm wondering if smog equipment was even required on a 1973 C20. I've looked online for a emission parts list for my truck but haven't found anything so any help on this matter is much appreciated!

[KrazyRay]

The 73 with a 454 usually came with no EGR or it had a factory EGR blockoff plate. I don't think it would have a smog pump or tubes on the exhaust manifolds. I may be wrong, but the only thing you need is a PCV. Good luck!

[MusicMan70]

Here's what my 73 stock 454 looks like; no AIR pump or EGR. Smog pump in California only; I think. This truck was originally from Washington State

[savatreatabvr]

Thanks for the picks MusicMan70! I believe 1975 and up C20s require Cats so I think I'm good there. Now I wonder if my aftermarket air cleaner will pass or do I need the factory air cleaner?

[Zane M]

It depends on how stringent your testing facility is. Technically the valve cover breather would route into the air cleaner so those fumes would be consumed through the air supply to the carb for combustion purposes.
I have trucks set up like yours, and don't have any issues here in Utah.

[KrazyRay]

You will probably need the heat stove on the exhaust with the riser tube going to a stock air cleaner and the PCV going from the valve cover to the spacer above the carb. I've seen 3/4 ton trucks in CA without smog pumps up to 1978, however, I have a stock 1973 1/2 ton with all of the smog garbage on it. The GVW has a lot to do with smog equipment.

[rfmaster]

Originally Posted by savatreatabvr

Thanks for the picks MusicMan70! I believe 1975 and up C20s require Cats so I think I'm good there. Now I wonder if my aftermarket air cleaner will pass or do I need the factory air cleaner?

'75 model year was the last year of no CAT's for HD trucks (engine emission family 113) in CA. You'll need stock air cleaner assembly with heat air for the thermatic valve and air purge tube between air-cleaner and valve cover. AIR injection is required for 75 SBC and BBC trucks in CA. No EGR and that's about it.

//RF

[savatreatabvr]

I have a nipple on the bottom of my chrome aftermarket air cleaner, I'm assuming if I run a hose from the valve cover to the nipple I'd be fine, it's doing the same thing as the factory air cleaner, right?

[86swb]

Man, I am glad we do not have those emission test here in Kentucky. I do not have any emission equiptment on eather my 86 or 84.

[Karlthegrillguy]

[QUOTE=savatreatabvr;5890598]I have a nipple on the bottom of my chrome aftermarket air cleaner, I'm assuming if I run a hose from the valve cover to the nipple I'd be fine, it's doing the same thing as the factory air cleaner, right? [QUOTE]

Yes, run the line to that nipple. As long as it lets air in, your good!
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[Oilbrnr]

In Maricopa and Pima counties for that year and GVCW all you need is the PCV.

Believe me, I have to do the annual ADEQ dance with my '77 K5 and '80 K20, both of which just escaped many requirements by GM tweaking the trucks ratings in those model years (esp. the K20).

Neither have EGR, cats, evap or smog pumps. Just make sure that PCV system is hooked up and functioning. The air cleaner is fine, but that breather off the valve cover = fail.

Good luck! It is a PITA having to go back if you fail the sniff test.

[Hevy]

Yeah, take the breather off and run the hose from air cleaner to valve cover and you should be good to go, as far as equipment...

[Oilbrnr]

Be prepared for the inspectors to scratch their heads for a bit and possibly refer to the big 'bible' that they have there. My K20 usually always involves the station manager to do the once over as well.
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[savatreatabvr]

Yes, emissions here in the Valley of the Sun is tough but since we live in a "Valley" where it's rarely windy the smog doesn't get blown away it just hangs over us! I dropped a valve in my '78 Z28 one night and got pulled over blocks from my house for excessive smoke and given a equipment repair ticket! But the biggest contributor to the pollution problem here is the city buses! Phx needed to blow some money so they built an electric light rail system to help with the smog but the buses still run and still smoke!

Originally Posted by Oilbrnr

In Maricopa and Pima counties for that year and GVCW all you need is the PCV.

Believe me, I have to do the annual ADEQ dance with my '77 K5 and '80 K20, both of which just escaped many requirements by GM tweaking the trucks ratings in those model years (esp. the K20).

Neither have EGR, cats, evap or smog pumps. Just make sure that PCV system is hooked up and functioning. The air cleaner is fine, but that breather off the valve cover = fail.

Good luck! It is a PITA having to go back if you fail the sniff test.

[65chevysub]

Originally Posted by Oilbrnr

In Maricopa and Pima counties for that year and GVCW all you need is the PCV.

Believe me, I have to do the annual ADEQ dance with my '77 K5 and '80 K20, both of which just escaped many requirements by GM tweaking the trucks ratings in those model years (esp. the K20).

Neither have EGR, cats, evap or smog pumps. Just make sure that PCV system is hooked up and functioning. The air cleaner is fine, but that breather off the valve cover = fail.

Good luck! It is a PITA having to go back if you fail the sniff test.

What about my 84 C2500? It was bought new in California but been in AZ since then. I bought it in 2019 and it had a broken EGR and that's it. Plugs in the manifolds, no tubes, or air pump. Had a canister but wasn't hooked up. Engine is an older 350, simple dual exhaust. I put a stock air cleaner on it and have a chrome breather in the valve cover. Currently living in Yavapai County but wanting to move to Tucson. Any help is greatly appreciated

[72c20customcamper]

Oilbrnr last activity on the site was November 2017 . This thread is 12 years old

[karlbenz]

I'd just take it in and let them inspect it. They will let you know.
20-30 years old here is safety only. anything over 30 years, no inspection needed at all

[Keith Seymore]

Originally Posted by 65chevysub

What about my 84 C2500? It was bought new in California but been in AZ since then. I bought it in 2019 and it had a broken EGR and that's it. Plugs in the manifolds, no tubes, or air pump. Had a canister but wasn't hooked up. Engine is an older 350, simple dual exhaust. I put a stock air cleaner on it and have a chrome breather in the valve cover. Currently living in Yavapai County but wanting to move to Tucson. Any help is greatly appreciated

Need more info.

Need to know your GVW rating.

K

[truckin 79]

Does your truck still have the original emissions sticker on radiator support? If so most emissions stations will go off of that. I would say most of the youngsters who work in CO maybe even AZ emissions stations have no idea what vintage emissions equipment is supposed to look like, much less what it does. I would just take it in and see if it passes emissions, the number one thing of course is catalytic convertor(s). Once again some young kid looking at a carburetor probably thinks they are looking at a nuclear reactor.

[kglowacky]

Texas just put into effect some new inspection/emission laws. The small rural have no more emissions testing but big cities and surrounding areas still do. BUT to my surprise my 78 Silverado has no more inspection at all. Not even a safety check. Just renewed my plates. The idea of antique plates is off my bucket list as it is only a small lc fee that's it. Can drive anywhere

[Keith Seymore]

Originally Posted by truckin 79

Does your truck still have the original emissions sticker on radiator support?

Just to be clear: emissions sticker goes on the rad support for LD emissions vehicles, because GM certified the vehicle.

HD emissions sticker goes on the air cleaner, because GM certifies the powertrain for HD emissions.

K

[Keith Seymore]

Originally Posted by 65chevysub

What about my 84 C2500? It was bought new in California but been in AZ since then. I bought it in 2019 and it had a broken EGR and that's it. Plugs in the manifolds, no tubes, or air pump. Had a canister but wasn't hooked up. Engine is an older 350, simple dual exhaust. I put a stock air cleaner on it and have a chrome breather in the valve cover. Currently living in Yavapai County but wanting to move to Tucson. Any help is greatly appreciated

Originally Posted by Keith Seymore

Need more info.

Need to know your GVW rating.

K

The '84 generic info packet in the GM Heritage Center archives does not have this same level of detail, but here is the chart for '86: