Quote:

---

Some of the confusion is due to incorrect terminology.

The VAPOR SEPARATOR is to keep vapor out of the carburetor. That's what the filter with the extra fitting is for. I believe that if one looks up into the smaller tube coming off the filter, one sees a smaller hole (orifice) where the tube connects to the filter body. The return line conducts the vapor and whatever liquid fuel flowing through the orifice, back into the fuel tank. Otherwise, where would it go?

Now on to the back of the car. In 1971, maybe earlier, Federal regulations required new cars to control emissions of fuel evaporating from the gas tank. This is called EVAPORATIVE EMISSIONS CONTROL. It controls evaporative emissions by collecting the vapor that exists in the top of the tank and catching it in either a larger container where the evaporated fuel can condense and run back into the tank, or else into a charcoal canister that is plumbed to the engine intake, so that the evaporated fuel is eventually burned by the engine. This had NOTHING to do with preventing vapor lock, and was not primarily intended to allow the complete filling of the tank. It was a response to a Federal mandate.

My 1972 Nova had the charcoal canister. My 1971 D100 had a simple vent line going to a larger segment of tube, which I think had an overflow that went through the floor.

Starting whenever the Federal mandate went into effect, gas caps were NO LONGER VENTED.

There is nothing about the evaporative emissions control system that harms performance. (Well, maybe it adds a pound or two of extra weight.) Removing it only demonstrates one's ignorance.

R.

---