Cold weather start problem

[JWR]

Tried again temp in mid 20's turns over fine sounds like it wants to start but no go. Put new spark plugs in and new fuel filter , checked spark and it was real strong at both cylinders , tried using starting fluid still would not start.

Being gas, you might have ice in the filter or? Most anywhere in the fuel path a tiny bit of water can do this.

After more thought, I'm guessing your carb float is not fully opening or tick shut. It lets in a little gas, you run the engine a minute or two and use that gas and the float valve is either gagging on something or not opening for whatever reason. If it sits a while a trickle of fuel gets in to the bowl and you can keep repeating this forever. If nothing else shows, I'd disassemble the carb and see if the float valve is free or not. I had an OLD MH with a Continental 4 cyl which would starve out of fuel, I'd hit the cast iron bowl a whack with a crescent wrench and it would then run for a while. Rebuilds never cured the issue. Finally decades later I used some Seafoam additive in the gas and the problem went away. I'm no fan of additives either.