74 Smog Equipment
Thread Starter
Racer
Joined: May 2008
Posts: 391
Likes: 1
From: Greenwich Ohio
74 Smog Equipment
I just got a 74. My first C3. What kind of smog equipment should it have? Engine is a 350 L48 4 speed with air (CKZ). It is all original numbers matching. It does not have an air pump. I checked the manifolds to see if possible the air tube holes might have been plugged and it does not appear they were ever drilled for the tubes!
Its also a late build car. June 21,1974.
Thanks
Its also a late build car. June 21,1974.
Thanks
Racer
Joined: May 2014
Posts: 420
Likes: 5
From: Springfield Missouri
Are you certain it's numbers-matching, or is that just what you were told when you bought it? Im not trying to rain on your parade, it's just that a lot of new owners buy "numbers-matching" cars only to later find out from the very knowledgeable people here that they aren't. If it IS numbers-matching and has no AIR pump or holes in the manifold, then you likely have a car that never was smog-equipped.
Up until the late 70s (I think) cars only had smog equipment if they were being shipped to CA or a "high-altitude" state. It may be possible to determine if you have a smog car by decoding the VIN, but I cannot say for sure. Im sure there are others here that can tell you better than I.
Up until the late 70s (I think) cars only had smog equipment if they were being shipped to CA or a "high-altitude" state. It may be possible to determine if you have a smog car by decoding the VIN, but I cannot say for sure. Im sure there are others here that can tell you better than I.
Thread Starter
Racer
Joined: May 2008
Posts: 391
Likes: 1
From: Greenwich Ohio
Are you certain it's numbers-matching, or is that just what you were told when you bought it? Im not trying to rain on your parade, it's just that a lot of new owners buy "numbers-matching" cars only to later find out from the very knowledgeable people here that they aren't. If it IS numbers-matching and has no AIR pump or holes in the manifold, then you likely have a car that never was smog-equipped.
Up until the late 70s (I think) cars only had smog equipment if they were being shipped to CA or a "high-altitude" state. It may be possible to determine if you have a smog car by decoding the VIN, but I cannot say for sure. Im sure there are others here that can tell you better than I.
Up until the late 70s (I think) cars only had smog equipment if they were being shipped to CA or a "high-altitude" state. It may be possible to determine if you have a smog car by decoding the VIN, but I cannot say for sure. Im sure there are others here that can tell you better than I.
Racer
Joined: May 2014
Posts: 420
Likes: 5
From: Springfield Missouri
Then odds are your car never had smog equipment. Even catalytic converters weren't put on the cars until 75 or 76, I think.
This thread should get more traffic this evening once everyone's home from work. That's when the more knowledgeable folks are likely to show up and comment. Post up some pictures for everyone to look at too: we all like looking.
This thread should get more traffic this evening once everyone's home from work. That's when the more knowledgeable folks are likely to show up and comment. Post up some pictures for everyone to look at too: we all like looking.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Sorry but both statements are false. All Corvettes had varying types of smog equipment going back to the mid 60s. The VIN contains no info regarding smog info either.
I believe that '74 L-48 with 4 speed had an AIR system, plus EGR plus TCS. Auto trans did not have AIR.
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
Sorry but both statements are false. All Corvettes had varying types of smog equipment going back to the mid 60s. The VIN contains no info regarding smog info either.
I believe that '74 L-48 with 4 speed had an AIR system, plus EGR plus TCS. Auto trans did not have AIR.
I believe that '74 L-48 with 4 speed had an AIR system, plus EGR plus TCS. Auto trans did not have AIR.
BTW I have never figured out what a "thermostatically controlled air cleaner" is...or "carburetor heated air".
Last edited by Paul L; Dec 10, 2014 at 01:28 PM.
Racer
Joined: May 2014
Posts: 420
Likes: 5
From: Springfield Missouri
Sorry but both statements are false. All Corvettes had varying types of smog equipment going back to the mid 60s. The VIN contains no info regarding smog info either.
I believe that '74 L-48 with 4 speed had an AIR system, plus EGR plus TCS. Auto trans did not have AIR.
I believe that '74 L-48 with 4 speed had an AIR system, plus EGR plus TCS. Auto trans did not have AIR.
Last edited by Kris Tunetso; Dec 10, 2014 at 02:38 PM.
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Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
The second could mean the same thing or the heated passage inside the intake manifold.
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
The first is a vacuum activated valve built into the snorkel of the air cleaner that selects either warmed air from the outside of the exhaust manifold via a tube or fresh air. It's thermostatically controlled according to coolant temp.
I had that system on my 1979. The 1974 Corvette does not have it. Perhaps passenger cars had it but not the Corvette. Hence my confusion. Perhaps that spec sheet is wrong. Does the 1973 have it?
I had that system on my 1979. The 1974 Corvette does not have it. Perhaps passenger cars had it but not the Corvette. Hence my confusion. Perhaps that spec sheet is wrong. Does the 1973 have it?
Last edited by Paul L; Dec 10, 2014 at 02:57 PM.
Burning Brakes
Joined: Dec 2006
Posts: 979
Likes: 254
From: Bethlehem, PA
Here's a picture of a '74 l48 4 speed I owned. It had a 29199 diverter valve, 7801149 pump and 3917234al pulley. Also was Bloomington gold/survivor and NCRS top flight implying all was correct. I agree with the others that said check your "numbers" since you don't have plugged exhaust manifolds.
74eng by toylman, on Flickr
awards by toylman, on Flickr
74eng by toylman, on Flickrawards by toylman, on FlickrI just got a 74. My first C3. What kind of smog equipment should it have? Engine is a 350 L48 4 speed with air (CKZ). It is all original numbers matching. It does not have an air pump. I checked the manifolds to see if possible the air tube holes might have been plugged and it does not appear they were ever drilled for the tubes!
Its also a late build car. June 21,1974.
Thanks
Its also a late build car. June 21,1974.
Thanks
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
Toylman has a good pic. Those air cleaner base vacuum valves are not there. Nor are they on mine. That spec sheet was probably mixing cars without cowl induction in with Corvettes. Bureaucrats sometimes foul up. In any case this should not detract from the original question. The OP's car should have the AIR pump.
Race Director
Joined: Oct 2000
Posts: 12,684
Likes: 3,137
From: Shamong, NJ
I agree with Paul 74, in regards to 74's with A.I.R. Federal Emission 74 L-48 automatics didn't use it, but all other 74's did.
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
1976 was the first year the Corvette used the "Thermostatically Controlled Air Cleaner", though other Chevrolet's came with it as early 70 or 71. It was on all Corvettes from 76 on. It's pretty easy to identify. Any car that has a "stove pipe", or tube running from the exhaust manifold to the air cleaner, has it.
I agree with Paul 74, in regards to 74's with A.I.R. Federal Emission 74 L-48 automatics didn't use it, but all other 74's did.
I agree with Paul 74, in regards to 74's with A.I.R. Federal Emission 74 L-48 automatics didn't use it, but all other 74's did.
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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Look just to the rear of the master cylinder the ZB sticker will say:
Automatic Manual
CCS-EGR AIR-EGR
more 74 trivia.
http://www.motorera.com/corvette/1970/vet74.htm
Automatic Manual
CCS-EGR AIR-EGR
more 74 trivia.
http://www.motorera.com/corvette/1970/vet74.htm
Melting Slicks
Joined: Jul 2009
Posts: 2,091
Likes: 40
My auto L48 74 coupe never had a smog pump that I ever saw , no sign of brackets or manifold with holes, it was bone stock far as I know when bought it engine wise . ....well,save the side pipes.
The 4 speed L48 did come with a pump setup . I think there are pics of all the possible belt configuration in the AIM.
The 4 speed L48 did come with a pump setup . I think there are pics of all the possible belt configuration in the AIM.
Last edited by LS4 PILOT; Dec 12, 2014 at 09:43 PM.