Up until about 2 months ago, it was running like a top. I had fixed several things that weren't broken trying to chase an issuse that turned out to be a hole in the fuel line. Gradually, it has gone downhill from there. When it's cold, it cranks up quick, but blows white smoke for a while. Ater it gets hot, and I try to restart, it turns over a few timeslike the battery is really weak and then suddely fires up, complete with black smoke.

The timing is the same as ever, and it doesn't seem like a typical weakening battery. A bad battery does that a couple times, and you're done. This has gotten progressively worse over several weeks.

 

sounds like the choke is in need of an adjustment

 

Sounds like a carburetor issue. Could be a stuck choke. The white smoke could just be condensation in the exhaust burning off.
As the old rubber in the carb gets more gas soaking it, it get softer and then starts leaking out and not supplying fuel like is should.

 

Have you put a load tester on the battery ?

 

My 78 F-350 with the 400 is doing the same exact thing but without the smoke, I have replaced the Starter and Battery and adjusted the timing. Still it will start great cold and barley turn over when hot but suddenly fire up.

 

I agree that the carb needs some attention, but when I say that it turns over like the battery is weak, I mean it barely turns over like it has just enough juice to move the engine. After 4-5 very slow turns (1 mississippi, 2 mississippi,....), it starts to turn over at a normal pace - then, it's flooded.