Would like to understand logic behind hot start suggestions

[YankeeClipper]

Thanks Lear-jetter.

1) Your Vapor-lock explanation checks out with any understanding I've had on the topic

2) Because of the return lines, I also get that at least upstream a bit you'll get cooler fuel primed and ready to feed further downstream once the mixture is opened again--at least if we can assume that tanks are cooler than hot engines. Hopefully we can.

3) Open throttle: this is where I don't understand the procedures. They do not say to rotate the engine in the closed throttle position (not the ones I've read here and elsewhere). They say to close the throttles to cracked before rotating the engine.

4) the relatively gradual opening of the mixture also makes sense, ensuring that you don't get a flooding condition.

[YankeeClipper]

"Move throttle from closed to open slowly, then back to closed. Maybe 5 secs"

So this procedure (different from the closed throttle ones I am confused about) starts to make more sense to me. Opening the throttle purges a sacrificial "slug" of hot and vaporized fuel from the lines, into the chamber, and pinches the line back off again just upstream of the divider.

However, given the potential of a somewhat flooded chamber (great or small, depending on circumstances), I would think it makes more sense to stay "cracked" as they always say, but pull the mixture back instead. Then start cranking, and advance the mixture to ensure a healthy firing when the needed mixture is arrived at. Using the throttle to do this would advance both fuel and air, and--I would think--not have the benefit of a lean beginning that transitions to a correctly enriched mix, facilitating a healthy fire up. In other words, as you start your crank with throttle cracked and mixture back, there would be a brief time to un-flood the chamber (assuming there is a flood, but no harm in a momentary lean condition in any case), and then start enriching with mixture advancement.