I don't see where you told us what your engine/carb is. It would be helpful to know that. I have a early '70s Rochester 4bbl on my '47, and it does the same thing yours does, but only after sitting for a couple days. A mechanic friend (48Bigtrucks) was over one day looking the beast over and his comment was that it's a common problem with this model carburetor. A rebuild will take care of it. Apparently there is a plug in the bowl that needs to be replaced because it allows the gas to seep into the intake manifold. When there's gas in the manifold it starts fine, but after sitting a couple days it needs a shot down the throat too.
By the way experts. Is it better to use starting fluid or gas for that shot down the throat? I heard somewhere many years ago that the starting fluid is hard on the engine. It strips oil off of things, and is also too easy to get too much and blow a head off.
I usually use gas, but with a small squirt bottle to avoid getting too much or slopping all over. Since it only happens after a few days of sitting idle, I don't have to carry it around with me.
By the way, I hope you have a decent way to carry that starting fluid that is not in the cab and not in direct sunlight.
