I was running the Duster for the first time this year. After the car had idled for about 5 minutes, I noticed a little gray smoke coming out of the carb. When I turned the car off, a whole lot of smoke came out for about 5 minutes before finally dying out. The engine sounded fine the whole time, and there was never any smoke coming out of the exhaust or the breather.

The car has new plugs, new gas, and a rebuilt Carter 2BBL. Any suggestions on where to start looking for the problem?

Thanks

If gasoline is percolating out of the float bowl and into the carb throat after shutdown, it will often vapourise and that vapour will appear as fine white/grey smoky mist in and above the carb. You'd want to check the float level, make sure you're using the thick 3/8" carb-to-manifold gasket, and probably do the fuel line mod to reduce the heat being applied to the carburetor & fuel after shutdown. The other possible source of white/grey smoke is, as you mentioned, the crankcase.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

If your gas has become contaminated with water, as it often will while sitting for months at a time in the carb, I have been told that it will trick the float setting into allowing more fuel into the carb and allow the water to run out the overflow.

I don't exactly understand how this works or if it really even happens, but that is the story that I was told by the old mopar guy I sometimes get parts from.

His resolution was explained like this:

I put fresh gas in the tank,
I put a temporary hose from the overflow for the carb into a catch jug,
I started the engine and let it run out the old gas for a good while and kept an eye out that the jug didn't overflow.

He said that it ran for several hours till the water was flushed out and then he couldn't even burn the stuff in the jug.

No float adjustment was needed and the problem didn't come back.

I never actually saw this happen, and I have sometimes wondered if this guy is a quack, but I feel like I should mention it anyway based on your problem description.

If the car ran fine when parked last fall, then I suggest you let it run for a little while longer and see if it can work out the kinks on it's own. Of course, keep a close eye on it and re-evaluate if things don't start to improve.

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1980 Aspen 225 super six

Certainly an interesting story, to be sure, and I wasn't there, so I can't say it didn't happen, but there are problems with his theory. There's no way water could "trick" the float into doing anything. The float floats atop water, the same as it floats atop gasoline. And gasoline floats atop water, not the other way round, so if a mix of water and gasoline were to reach the carb, the water would be at the bottom of the bowl, and the gasoline would be above the water. Since the carb's jets are near (or at) the bottom of the bowl, water would be drawn through them and into the intake manifold, and the engine would stop (or run very poorly).

if any liquid is coming out the carb's internal vent (it's not an overflow tube!), there is a major problem with the float or the inlet valve.

Also, water swells the paper used in fuel filters such that the pores close up and fuel can't flow through, so if there's significant water in the tank, not much of it is going to get as far as the carb. The idea of pumping anywhere near the described amount of water out through the carb's internal vent while the engine runs happily on gasoline being supplied simultaneously is...highly suspect, as it seems to me.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I just wanted to say thanks to Dan for his advice. Doing the fuel line mod worked wonders.