Hi
I haven't really driven my 66 Mustang 289 since May. I've put a new ignition and serviced the carburetor. I started the car briefly yesterday. There was a lot of white smoke coming out and there were water droplets on the floor. I changed the oil in July but I haven't driven the car.
The manifold gaskets are new, vacuum tested the engine in July and had a loss of 10% only.
Now is it safe to drive the car and simply burn it?
It's fine. Get the engine nice and hot, and the condensation will go away. Gasoline+O2=CO2+H2O (as water vapor). This is normal for any engine, and the humidity of the surrounding air can affect the exhaust when it emerges. For example, if it's very humid and cold, the water vapor from the exhaust will start condensing as soon as it comes out of the tailpipe. Even when it's warm, if the humidity is near the saturation point (relative humidity) , the engine will vent water vapor through its exhaust as the heated exhaust drops back to the ambient temperature. Cool air holds less water vapor than warm air.
By the way, the tank is only 1/4 full. There could be some condensation there too.