3/4 ton big block with SMOG?

[JQ-72]

Just pulled in a 3/4 ton Suburban with 402 and TH400. It is a TLM suffix code engine with SMOG on it. All 3/4 BB trucks I’ve seen have been non-SMOG. Was this a Burb thing or assembly plant thing? It is a Flint built truck. All dates appear to match up with blue sticker on door so I don’t think the engine has been changed out. Any ideas?

[Steeveedee]

What year vehicle/engine? And what SMOG equipment?

[JQ-72]

Oh yeah. 1972 with the air injector pump

[jocko]

TLM = 72 RPO L47 402 with Air Injection Reactor - applications show C10 and C20.
Yes, I find that surprising, I haven't seen smog on a C20 before either.
TKM is also an L47 with AIR for C10 and C20.
There are non-AIR codes for 72 big block C20/30 (only, i.e. not available on a C10) (TKW, TKX).

[jerry moss]

years ago i had a 69 3/4 ton suburban 396 with air injection , it was a clean original truck and my dumb a$$ parted it out. sold the motor with all the brackets including a-c for more than i paid for the whole truck.

[PbFut]

A 1972 c20 has a commercial classification, so no calif smog equipment is/was required. C10 required smog as it was not classified commercial. It is why a c20 is more expensive to register in California because of commercial class. The c20 has commercial plate allowing you to park in yellow curb commercial zones. Useful in urban areas of LA, SF and SD. The Chevy Suburban, even the c20 Suburban was classified as a passenger vehicle so smog was required. You can get a C20 registered as passenger if you have a permanent camper on it to save a few bucks but a sharp eyed smog tech could have caused problems. Not a issue now. We are past inspection dates. If you need info on BB smog parts, I would look to the C3 Corvette owners. They likely have the info given there were a lot of BB Corvettes from that time. They were putting pumps on 250 sixers as far back as 1967 in calif. The air injector port was actually in the head, not the manifold. I owned every car/truckmentioned in this post except the suburban at one time or another.

[jerry moss]

Originally Posted by PbFut

A 1972 c20 has a commercial classification, so no calif smog equipment is required. C10 required smog as it was not classified commercial. It is why a c20 is more expensive to register in California because of commercial class. The c20 has commercial plate allowing you to park in yellow curb commercial zones. Useful in urban areas of LA, SF and SD. The Chevy Suburban, even the c20 Suburban was classified as a passenger vehicle so smog was required. You can get a C20 registered as passenger if you have a permanent camper on it to save a few bucks but a sharp eyed smog tech could have caused problems. Not a issue now. We are past inspection dates. If you need info on BB smog parts, I would look to the C3 Corvette owners. They likely have the info given there were a lot of BB Corvettes from that time.

good info, I never gave it a thought about the subs are registered as a passenger car and I own one.

[jocko]

When I lived in CA, C10s required commercial tags if the bed was open. If bed had a cap or tonneau, it was not required. It drove me absolutely nuts that had I had to go weigh and register my 66 C10 swb as a commercial vehicle. Maybe things have changed and CA has seen the light.

Regardless, 2 of the 4 72 402 suffix codes indicate that there was indeed an AIR-equipped 402 built for C10s and C20s (trucks) in 72. And the other 2 suffix codes indicate that a C20 or C30 could have a 402 without AIR. Maybe the smog 402s in C20s were just uncommon, or driven by an individual state requirement.

I'm still not quite clear on what drove whether or not AIR was required on a C20, truck or burb.

[too much stuff]

I pulled this from a 72 1/2 ton burb a few years back.

[jerry moss]

commifornia hasn't changed for the better, if anything is got worse. pickups still have to be registered commercial, my 80 K20 just cost me $304.00 for a year because of the GVWR, didn't have to smog it this year but will next year. I work in a shop that does smog's and they are tightening up on the passing numbers trying to get the older vehicles off the road. if you own an older jeep with a 6 cylinder that doesn't have an EGR you can forget about it passing even with a brand new catalytic converter.

[PbFut]

I was young, and as most, did not understand the a.i.r. pumps of the day. They were quite effective at afterburning hydrocarbons on engines used at that time. The extra belt and pullies were easy to remove and so off they came. In reality, very little power was needed to spin a smog pump. Give how bad the air was in LA county, compared to today, I must say that as invasive as the Calif pollution laws are, they are effective. Today's air quality, though still not great is way, way better.

[connorm]

My 1970 GMC C/2500 with a 307 had smog on it. It was built in Canada and was mandatory there, even though it was imported to the U.S.

[kwmech]

Having a pick up with commercial plates does allow you to park in loading zones though.

[factorystock]

Originally Posted by connorm

My 1970 GMC C/2500 with a 307 had smog on it. It was built in Canada and was mandatory there, even though it was imported to the U.S.

Another '70 307 3/4t 4x4, was surprised to see the smog equipment, was a U.S. Tarrytown build.

[JQ-72]

PbFut - thanks for the input. I didn’t know that the C20 Burb was considered a passenger car for smog purposes. Good info!

[mr.mud1]

Originally Posted by connorm

My 1970 GMC C/2500 with a 307 had smog on it. It was built in Canada and was mandatory there, even though it was imported to the U.S.

i don't remember if that was required here or not back then,but whether it was or wasn't,if your truck was built in Canada and shipped to the U.S new,it would've built to the U.S spec.the other side of that coin is,i have hauled cars,trucks and Harley's home from the States for 40 years and we used to carry a booklet from Transport Canada,telling us what we could bring and home and what we couldn't,as some models were built to U.S specs that differed from Canadian specs.

[mr.mud1]

my 72 402 Cheyenne Super,built at the Fremont plant in Sept 71,has a TKX engine with no air pump or any other emissions equipment that i've found.it does say on the build sheet VJ9 Emission label,TF5 Cal Assy Emission and a YF6 Cal Proc Option? but there isn't or wasn't any emission equipment on it.

[DeadheadNM]

Here's a related thread for additional reference: THREAD

[425HP409]

SMOG - where built and where sold

I have a 67 Olds 442 with AIR. It was built in Fremont CA and sold at a California dealer so it had to have smog equipment. It is pretty unique at car shows here in Texas.
If it was going to be shipped to a dealer out of California, the exhaust manifolds would have been plugged and no AIR even though it would have been built in California.
I once saw a 66 Caprice with a 396 equipped with AIR. Good ole California smog rules.
I have been in the mechanic field all of my life. I remember looking up emission specs for cars in the 60s and seventies and there were 2 categories; California and 49 states.

[MARKDTN]

Originally Posted by PbFut

...The air injector port was actually in the head, not the manifold.....

I've never seen a BB Chevy head with AIR in the head?

[67 twins]

Originally Posted by MARKDTN

I've never seen a BB Chevy head with AIR in the head?

He didn't say they were. He mentioned a 250 in the preceding sentence. He's saying on the inline 6s they are in the head.

[jumpsoffrock]

Originally Posted by jerry moss

commifornia hasn't changed for the better, if anything is got worse. pickups still have to be registered commercial, my 80 K20 just cost me $304.00 for a year because of the GVWR, didn't have to smog it this year but will next year. I work in a shop that does smog's and they are tightening up on the passing numbers trying to get the older vehicles off the road. if you own an older jeep with a 6 cylinder that doesn't have an EGR you can forget about it passing even with a brand new catalytic converter.

Wanna know somethin funny? My '56 F100 cost me 174, and my '72 C3500 cost 167; both are commercial.

lol

[Richard]

Originally Posted by mr.mud1

my 72 402 Cheyenne Super,built at the Fremont plant in Sept 71,has a TKX engine with no air pump or any other emissions equipment that i've found.it does say on the build sheet VJ9 Emission label,TF5 Cal Assy Emission and a YF6 Cal Proc Option? but there isn't or wasn't any emission equipment on it.

Seem to remember something about your truck coming from the USA. Your truck is a utility vehicle with a higher load rating, a Suburban is a passenger vehicle. My first 72, a K20 truck had no smog as well. Was born here in Ca. My current 72 K10 had smog due to lower weight rating but was removed years ago due to living in a county that does not have emissions testing. All the burbs would have smog here in Ca.

[MARKDTN]

Originally Posted by 67 twins

He didn't say they were. He mentioned a 250 in the preceding sentence. He's saying on the inline 6s they are in the head.

OK. I read it again. Gotcha!

[PbFut]

MarkTn: Sorry if I was not clear on the sixer I failed english more than once in my school days. I have never found the skill so my writing is clear to me, but most find it difficult to follow.
Mr Mudd: If your truck is a 3/4 ton then you are likely rocking commercial plates and are smog exempt in Calif.
Another point was that if you purchased a used "Federal smog car", you could register in Calif. but you had to have the correct stickers on the car/truck and the smog inspection tech had to understand it was a Fed smog car. You still had to pass the minimum sniffer test to register. Later on things got tougher when the bi-annual inspections started but a used Federal car was allowed, again as long as the car could pass the sniffer.
Someone mentioned that more of the manual trans cars got pumps, that is because the lifting of the accelerator to shift would lean the A/R ratio and cough out of plug of hydorcarbons. So I think it is possible that some motor tranny combos might have needed a pump even on a federal car. That is a guess on my part. Or maybe it was simply a Cal car moving to another state. There was a time around 1980-1982 when you could not get a manual trans and the 350 motor in Calif. If you wanted a manual, it was a 305 motor in the Corvette, Camaro and Trans Am. Not sure about trucks.