What does the module on air cleaner do?

[redneckmba]

I have a stock 74 Valiant 318. Vacuum for the distributor advance is routed from the carb to a module on the air cleaner housing then to the distributor. What is the function of the vacuum module on the air cleaner?

Carl

 

[port-holio]

I believe it's to prevent the distributor from applying acceleration advance until the engine is warm in order to improve cold weather emissions. There were a few different devices for this over the years. the module on my 73 340 parts duster was mounted on the firewall.

 

[redneckmba]

Thanks! I figured it was looking at air intake temperature from the mounting location.