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?

[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?

[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.

[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.

[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...

[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.

[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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