1975 Emission Control Equip new information

[Harmon C.]

Re: 1975 Smog Equipped Corvettes

Don Good to hear from you is the 75 an automatic ?

[Patrick H.]

Re: 1975 Emission Control Equip new information

Sal,

your taste in Corvettes sure has improved over the years.

Patrick

[Harmon C.]

Re: 1975 Emission Control Equip new information

Tom I agree that if one owns a 75 automatic and no smog I would look at the type of plugs in the exhast manifolds and their date codes. What it says on the emissions label. TCS and wires needed for the system and change nothing till I was sure what needed to be done if anything. Tom I have the TIG second edtion. Do you have the new one and what is the information in it on smog for 1975's?

[Bill E.]

Re: 1975 Emission Control Equip new information

Good morning Joe:

The sticker has "AS" in upper left hand corner. The sticker part no. 360420. The car's owner says it does not have plugged rail holes in the manifold.

Bill

[Joe L.]

Re: 1975 Emission Control Equip new information

Bill------

If you examine the "AS" emissions code sticker more carefully, it will reveal other pertinent information. Just to the right of the "AS" block on the top of the sticker is a rectangular block which says "VEHICLE EMISSION CONTROL INFORMATION" and, below that, "General Motors Corporation" followed by the "GM" logo. To the right of that block is another block which identifies the emission equipment utilized with the "AS" emissions code. This block includes the script "AIR-EGR-EFE-OC EXHAUST EMISSIONS CONTROL"

AIR= air injection reactor

EGR= exhaust gas recirculation

EFE= early fuel evaporation

OC= catalytic converter

As I mentioned previously, for 1975 the only emissions certification codes that I have any record of are "AS", "DR", and "AU". Each of these emissions codes includes AIR as part of the installed emissions components. "AS" is the code for non-California L-48s; "AU" is the code for ALL L-82s. I've since confirmed that "DR" is the code for California L-48s. The aforementioned codes are for BOTH automatic and manual trans.

Keep in mind that these codes and stickers refer to CERTIFICATION of the vehicle's emissions control system under USEPA and/or California Air Resources Control Board (CARB) requirements. These are not matters that GM ever took lightly because of the legal implications. Can you see GM CERTIFYING that a vehicle conforms to "AS" emissions control which clearly states that AIR is part of the system AND THEN NOT INSTALLING AIR on a vehicle so-certified? There may be uncertainty between what the manufacturer ACTUALLY installs on a car and what the manufacturer SAYS can be installed on a car. However, with respect to vehicle CERTIFICATION for compliance with vehicle emissions or safety requirements, I don't think that there will be ANY uncertainty, ambiguity, or deviation.

There is a possibility that there were other emissions certification codes used for 1975 that I am not aware of. I don't think so, but it's possible. However, for those cars with emissions certification codes "AS", "AU", or "DR", then those cars were originally equipped with AIR whether they are currently, or not.

In the case of this particular car, even if it has non-AIR exhaust manifolds on it now, I'd STRONGLY suspect that it did not always have those manifolds on it. These manifolds are easily changed and it's not unheard of for folks to change these to eliminate the "vestige" of AIR to fool neophyte smog inspectors "in the old days".

[Bill E.]

Re: 1975 Emission Control Equip new information

Joe:

You're right it does say A.I.R. on the sticker. It also says the car does not meet California emission standards.

One last question before we beat this to death. If this car was equiped with an air pump and catalytic converter, what else would it need to meet California standards. I'm from California and years ago I purchased a 1978 TR-8 that had all the smog equipment removed. The basic components of the system I had to install to meet state requirements were the air pump, catalytic converter, and vapor recovery canister plus a few valves and hoses. I wonder what the difference is between 50-state and 49-state cars.

Bill

[Tom R.]

Re: 1975 Emission Control Equip new information

Lyle:

I have the second edition and it shows that L48 auto, non-CA cars did not come equipped with A.I.R. I'm afraid to say as well that emission labels, as presented in the manual serve no value regarding the delineation of a 75 A.I.R. car

[Tom R.]

Re: 1975 Emission Control Equip new information

Bill
Ok...we're getting close but still need the engine suffix. Have your seller look at the stamp pad (front of engine, passenger side) and he'll find two sets of numbers and alpha characters. Ask if he sees either CHB, CRJ or CRK. I'm suggesting that if this is the suffix along with what you've presented...it's a non A.I.R. car. It should show something starting with a C among other characters.

[Tom R.]

Re: 1975 Smog Equipped Corvettes

Joe:

In 73, we had three engine options...yet two emission code labels but all had A.I.R. Why did we not have three emission labels?

[Tom R.]

Re: 1975's Delivered to California

Understand, technical manuals are not changed on the basis of heresay. Rather, they are changed on the basis of substaniated information such as field observations that underscore the observation.

So on what basis do we accept this new information?

[Brian G.]

Re: 1975 Smog Equipped Corvettes

Our 1975 L-48 Automatic (New York car) DOES have the smog setup, Emission Code-AS, Engine Suffix-CHB

[Joe L.]

Re: 1975 Smog Equipped Corvettes

Tom-----

There WERE 3 emissions codes and stickers for 1973:

"WJ"= L-48

"WK"= L-82

"WN"= LS-4

What gave you the idea that there were just 2 codes for 1973? I hope that it wasn't because the 1975 judging guide mistakenly ascribed 2 of these codes to the 1975 model year and you concluded that those 2 were the ONLY codes applicable to the 1973 model year.

[Joe L.]

Re: 1975 Emission Control Equip new information

Bill-----

The "DR" emissions code California cars used a different EGR valve, a different distributor advance curving and different ignition initial timing setting.

A non-California emissions coded car CAN be registered in California without the need to convert it to California emissions as long as:

1) The car is not purchased new and immediately brought into California for registration and operation (i.e. the car has to have a certain number of miles on it);

2) The car's federal emissions certification equipment is INTACT and un-tampered with.

[Tom R.]

Re: 1975 Smog Equipped Corvettes

Joe:

You're correct for 73. Our thread was 75 and while I wrote 73...my intent was 75. I'll rephrase...

In 75, we had three engine options...yet two emission code labels but all had A.I.R. Why did we not have three emission labels?

[Joe L.]

Re: 1975's Delivered to California

Tom-----

To be honest, it sounds to me as if the information CURRENTLY in the manual was based on heresay, or, at the least, faulty research and observations.

First of all, keep in mind that if one observes a non-California (or, for that matter, ANY) 1975 L-48 which is ABSENT AIR, that does not mean that the car was originally produced that way. Lots of folks removed these systems, so the ABSENCE of the system doesn't say anything about how the car was originally produced, even if MANY such cars were observed in a non-AIR equipment condition. We've heard here from several folks that have/had L-48s, apparently of non-California origin, that have the AIR system. It's very unlikely that someone along the way ADDED the systems to cars originally not so-equipped.

Second, as I say, I can find records of only 3 1975 emissions certification codes for Corvettes (i.e. "AS", "DR" and "AU"). ALL of these codes specify that AIR is part of the emissions equipement associated with that code. If a car is observed with ANY of these emissions certifications/codes, then I say that CAR DID ORIGINALLY have AIR, whether or not it has it at the time of observation. Like I say, it says right on these certification labels that AIR was part of the emissions package.

For there to be substantiation that ANY 1975 Corvette was NOT produced with AIR, ALL of the following would need to be met:

1) evidence that some emissions code other than "AS", "DR", or "AU" was ACTUALLY used on a 1975 Corvette, and,

2) evidence that the code and label were 1975 codes (model year applicability is printed on the bottom of the label), and,

3) evidence on the label that AIR was NOT part of the emissions equipment associated with that code.

Absent the above-referenced, I would say that the notion that any 1975 Corvettes were produced without AIR is heresay or based upon anecdotal information.

Put another way, when folks who wrote or participated in the compilation of material for the technical information manual for 1975 Corvettes, what substantiation did they require for concluding that the absence of AIR was as originally produced? As I mentioned, the ABSENCE of a system really says NOTHING about how the car was produced. Did folks check the emissions certification label and note which code AND which emissions equipment was supposed to be installed with that code? If they didn't do that, then the information in the manual is heresay, anecdotal, and totally unsubstantiated. While empirical evidence is always best, just making an observation or observations and concluding that's how the cars were originally built does NOT always represent VALID empirical evidence. Particularly, in this case.

One other point: 1974 Corvettes with L-48, auto trans, and federal emissions, DID NOT use AIR. Also, all non-California 1976 Corvettes DID NOT use AIR. The GENERALIZATION that 1974-76 Corvettes with L-48, auto trans, and federal emissions did not use AIR is, however, not necessarily valid. In this particular case, it's absolutely not valid.