NOx 1970’s emission control system
 

How many remember these silly devices from the late 60’s thru the 70’s.

Here is an NOS unit in the box with instructions.
I saw many of these out here in California in the late 70’s and 80’s.
The creation of the “California Air Resources Board” (CARB) in 1967.

Supposedly they allowed your vehicle to pass the early design smog test.
Actually all they did was make your car run like crap and burn more fuel.
Needless to say once you passed the smog test you simply disconnected this silly thing, set your car the way it likes until next time.

It seems my ‘66 GTO 3x2’s car had this exempt sticker applied on the inside of the RH bottom windshield as the outline is still there.

I temporarily glued an old exempt sticker to the outside and as you can see these stickers shrank over time as compared to the outline on my windshield and a couple NOS stickers I found.

Exemptions from the Air Resources Board shows multiple carburetors.
Cool stuff.

we use to buy a dual point plate and install in the distributor to exempt as well

Here's another vintage system. This was on the '67 Chevelle Concours wagon (Y'all do remember the Concours, don't you?) that I brought out of Lancaster CA in 1990. In addition to interrupting the vacuum advance it instructs to set the base timing to 0.

When I did my no paintwork refresh in 2021 I re-mounted the box using the original holes and brass screws, tucking the harness behind the booster.