No one has said that spacers do not make a difference. There is nothing to disagree with. The point about zero is that it has no conductivity and will not work as a heat sink. We don't need you to sharpen every point on every post as you do: like.... "but very low indeed". That's just posting for numbers not for info. You comment and ride piggyback on everyone elses answers and disagree with an imaginary poster.
In my opinion: the subject of vapor lock, boiling gas out of carb and all that does not apply here. He starts in 3 seconds, it does not die when running and 3 seconds is NOT hard starting. It is not vapor lock or anything like vapor lock. The vehicle is not exhibiting what was called vapor lock, that is the wrong track to be on. He is not stranded along the road waiting for the engine to cool off. There are many good comments and ideas expressed here regarding other possible issues.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn