1974 Emissions Specs by MVMA

[Paul L.]

I have attached an emissions spec sheet from the Motor Vehicles Manufacturers Association (MVMA). This is part of a little research project to document the emissions equipment that should be on my 1974 L-48 with TH400. Local authorities conduct random checks to ascertain if all factory equipment is in place. The check is visual not the sniff variety.

The first point is that a non-CA car like mine did not come equipped with an AIR system. So that is fine according to the sheet. But then the sheet speaks of a "thermostatically controlled air cleaner." This is not the case as the air cleaner is open and sealed to the hood (when down) via a rubber ring/tub; part of cowl induction.

I have seen this anomaly in other GM documents. Does anyone know the reason for this error? Did other 1974 passenger cars have the system mentioned above?

[Joe L.]

Re: 1974 Emissions Specs by MVMA

I have attached an emissions spec sheet from the Motor Vehicles Manufacturers Association (MVMA). This is part of a little research project to document the emissions equipment that should be on my 1974 L-48 with TH400. Local authorities conduct random checks to ascertain if all factory equipment is in place. The check is visual not the sniff variety.

The first point is that a non-CA car like mine did not come equipped with an AIR system. So that is fine according to the sheet. But then the sheet speaks of a "thermostatically controlled air cleaner." This is not the case as the air cleaner is open and sealed to the hood (when down) via a rubber ring/tub; part of cowl induction.

I have seen this anomaly in other GM documents. Does anyone know the reason for this error? Did other 1974 passenger cars have the system mentioned above?

Paul------


I have found inaccuracies in these MVMA specs in the past. While one would think the information should be 100% accurate, it is not. A thermostatically controlled air cleaner was not used on Corvettes until the 1976 model year.

[William C.]

Re: 1974 Emissions Specs by MVMA

Yes, pass cars used the air ducted off the exhaust manifold in 73-74 timeframe, also some of those documents floating around may not have reflected the actual production release configuration, as they were often filed with states or the fed govm't before the final configuration was completely validated.

[Paul L.]

Re: 1974 Emissions Specs by MVMA

Thank you for the replies. It appears that that info is still engrained in GM computers. See GM Canada letter attached.

I guess that I can only hope that the smog police do not target me next summer. They did not the summer last. At least I have info re the AIR system (its absence). BTW, the fine is quite substantial. And if someone is in a bad mood they can pull your plates on the spot.