automatic choke operation

[40 Deluxe]

Originally Posted by fordor41

I removed the manifold ( mid '70's Ford truck) and don't see any evidence of a passage way out of the blind hole. Agree that exhaust gasses are a bad thing in the choke housing.
went thru'59-'65 Motors manual and a '81 Ford manual. they show the heat tube/choke and manifold but nothing as to how it works. I've had a lot of '60's-'80's fords but never thought of how it should operate. As I remember the heat tubes were a tight fit in the manifold

Try a blast of compressed air to see if that opens it. Or run a small drill bit in by hand-any carbon will be dug out easily but if you hit metal you won't damage the tube.
Another thought: By the '70's at least some Fords were using hot air pipes from the exhaust manifold to the air cleaner with doors that let in heated air when cold and then opened to let in cool air after the engine warmed up, and also electric chokes. So your manifold and original carb may not have had a heat tube for the choke!
Do you the exact year of the carb and manifold? There should be a metal tag on top of the carb with a date code such as 'E4' which would be 1974.