The engine had to turn over a few times before firing. I note your thoughts on fuel vaporisaton but I have an electric pump fitted to prime the carbs and only just changed spark plugs. My car normally idles faster than most due to one of the butterfly valves not sealing properly......the faster idle I've got used to hence the surprise when it kept stalling.
I would normally start with the things that are easiest to check and look to see if there are any signs of dirt in the filters (do you have a Filter King installed?), if the fuel line between the carbs is empty (mine is transparent) or that it is not misfiring during normal running and if you move the wires to the coil or distributor. (do you have points or an electronic ignition?) If it dies gently, rather than abruptly, I would suspect fuel rather than ignition, but both can be checked.
I have not been impressed with the float hinge on the Solex 42DDHF carbs, so you may find it is sticking and allowing a carb to flood at idle. Dirt in a recent fill-up or if the car has been laid up and the tank is rusty can stop the float valve closing. All are straightforward to access from the top of the carburettor and will allow you to see if the float chamber contains long-term deposits. Let us know how the detective work goes!
