Ford 640 starting problem

[RufusMons]

My Ford 640, which usually starts with a quick touch of the starter button, sometimes does not start in cold weather.
In 15-degree F. weather today, it gave one good cough and then nothing more. The starter spins well but no ignition happens.
The carb does not appear to be flooded. Any suggestions on what may be happening?

 

[Hdonly]

(quoted from post at 09:14:52 02/13/21) My Ford 640, which usually starts with a quick touch of the starter button, sometimes does not start in cold weather.
In 15-degree F. weather today, it gave one good cough and then nothing more. The starter spins well but no ignition happens.
The carb does not appear to be flooded. Any suggestions on what may be happening?

My 651, in cold weather, likes me to open the throttle just a little, pull choke and spin till it coughs, let of the choke and hit the starter again. It usually takes right off then. May have to tickle the choke a little till it runs smooth.

 

[fredstev]

I think these updraft carburetors are a little picky in cold weather when the engine doesn't make as much vacuum as in warm weather. My 871 likes the throttle cracked, and the choke out for about 2 seconds while cranking in cold weather. Any other combination, it either floods or doesn't get enough gas to light.

 

[showcrop]

Carburetors generally don't flood. Cylinders do. How do the plugs look?