Smoke

From the little bit of information you gave us, sounds like it may be getting tired.

How many miles on this engine? Has it been well maintained? Have you ever done any engine or cylinder head work on this engine? Have you done a compression test or cylinder leakdown test? Does it use any oil between changes, and what kind and weight of oil are you using? More facts from you makes for better recommendations from us. ;-P

If it's smoking on over-run as you shift (and the manifold vacuum goes sky high), that would make me think first about sucking oil past the valve stem seals and/or piston rings. Or it could be that the carburetor is way out of adjustment and just needs a good rebuild, but we need more clues before saying anything specific.

-->--

White smoke = water. Unless you just started the car in winter, its usually a head gasket. Loosing coolant lately? Check your oil and radiator fluid for signs of mixing. When the two mix it looks alot like chocolate milk.

Black smoke = fuel. I can't help you much here other than you are running too rich when its blowing black smoke. I know absolutely nothing about carbs!

Blue smoke = oil. Do or have a leakdown test done. After you take the initial reading from each cyl, shoot a little oil in there and take another reading. The difference between the two readings is the amount leaking by the rings. The rest will be what is leaking by the top end of the heads (valves, valve stem seals or head gasket). A compression test is similar but not as complete.

My biggest concern is the head gasket. It sounds like it is partially blown now because of the white smoke. Water in the oil is a killer. It doesn't lubricate well and will corrode everything. That in itself will cause you to have to do a complete rebuild. But then we have the overheating factor to throw in. When it runs out of coolant, things are going to heat up very quickly. Too much heat and metal starts loosing its temper (gets softer) and things start warping. So if I were you, I would get the cooling system pressure tested and have a leakdown test done.

Good luck, Bard