Carburetor Heat Shield

[rubbinisracing]

I've seen a few cars at local shows that have the carburetor head shield with the engine firing order stamped into them. Are they factory pieces and what and when is there application?

[Mr70]

Yes they are and part of the RPO NA-9 package.
Also known as EEC for Evaporative Emission Control or Charcoal Cannister system ,or California Emissions.All the same animal.
It originally was mandatory on vehicles sold brand new in the state of California & certain parts of Nevada & Montana.
It soon became standard equipment in all states,on most vehicles as the years moved on.

[3macs1]

First I would like to say your collection is wonderful. On the carb spacer I am not sure if they were ever factory installed but we definately bought them over the counter from GM when I raced my 70 Chevelle years ago. There was one for holley and one for quad.They helped with controlling vapor lock and fuel boiling in the bowl especially on the holley with the GM Al intake by preventing all of the heat from getting to the carb especially after shutting the engine off. Some believed this cooler carb would produce a denser fuel mixture and make more H.P. We also used a Gm deflector pan under the GM Al intakes which again I bought over the counter to keep the oil off the bottom of the al intake and the heat down. I am not sure if GM still makes these items perhaps someone more experienced than me can let us know.I still have one of each NOS buried somewhere if part numbers are required.
Joe

[rubbinisracing]

Rick (MR70),

In 1969 and 70 were they only on Calif., Nev.,and Montana sold cars?

[Mr70]

I believe so Howard,but exclude 1969.
This was new for ALL 1970 vehicles.
Again,they had to be sold brand new in those areas to receive that,regardless of where they were built.
The paperwork will reflect this RPO,as well as some revealing details on the original vehicle itself.
This particular carb. heat shield should not be confused w/the A.I.R. system.

[rubbinisracing]

Rick,

Thanks for the great info. I went an looked at 2 of my cars build sheets that were sold new in California and there it was "NA9". Just so happens both cars were built at Van Nuys and are "Special Paint" cars.

Thanks again Rick!

[rubbinisracing]

Rick,

Does an L34 70 Chevelle with the NA9 RPO code on the build sheet use a carburetor heat shield with the quadrajet carb.?

[Mr70]

Absolutely..it was not just for Holley equipped engines.
All 1970 Quadrajets used part #3969837.

[3macs1]

Mr.70
Was the heat sheild and the charcoal canister system the only components of the NA9 RPO code or was there other components added.

[Mr70]

In addition to those two items,there was a seperator box mounted over the rear axle,special vented gas tank and gas cap,and a Special Carb with a fuel bowl vent pipe.
This system took the fuel vapors from the carb.and routed them to the charcoal cannister where they were then returned to the gas tank via the seperator.