Bruce ( Shrinker )

carby tuning techniques said
with pump unleaded petrol,you have to be real careful with the amount of vaporization that you have on the up stroke (compression).The light vapors that boil at a lower temp have the expensive octanes in them,they can withstand quite a bit of heat energy for a short amount of time.
The higher temp ones are the cheap octanes,they cant withstand as much heat and are designed to go off on the down stroke and in the cats.
When you can control the droplet size you can to some degree adjust this relationship of what vaporizes when.
You still want vaporization and burning to be occurring while the piston is at TDC as it helps the chase down of the piston. Thats why the flame kernel strength is so important and why ignition timing is linked with CO production.
Thats why having mains fuel with different droplet size is key to producing power making CO2.

You do realize there's a lot of info to unpack in that paragraph!

carby tuning techniques said
The transfer fuel if its done correct - it really does set the driving style of the vehicle.much vehicle movement for small throttle movement.
It does this by producing a hot cylinder and this is extremely important as it sets up the cylinder condition to take the larger mains fuel droplets.If the cylinders are not nice and hot the mains fuel builds lower cylinder pressure than optimum.

I remember you saying this way back when on SpeedTalk about saturation

The engine runs on the transfer slot fuel first, and its this fuel that saturates the airstream for consistent fuel gassing in the intake tract.
This fuel that comes out of the transfer slot continues to come out quite high in the load settings on some engines and has a profound effect on the amount of combustion completeness that is reached.
To obtain a smooth running set of cylinders you need saturated air going to ALL cylinders.
The transfer fuel can be smaller in droplet size than the fuel that comes out of the main boosters, so it can deliver a different cylinder condition than the booster fuel.
You can choose to have either small droplets or larger blobby fuel drops exiting the transfer slots of a carby,its up to the operating to calibrate the t/slot/ifr/iab so as to achieve well saturated air exiting the carby.
The transfer slot reacts to the vacuum that is under it and the air leak that is on top of it, so all different engine combinations will deliver different amounts and sizes of fuel droplets, and here in lies the saturation level and quality.
Carb sizing plays a huge role in achieving good air saturation out of the transfer slot as well as the camshaft and port sizing.
Very,very little fuel emulsification has taken place at this point, if any at all..

Before I pulled my engine I put a 850 Thermoquad on it that Demonsizzler originally built for AndyF. The most notable difference was the running smoothness and how much quicker it revved.

So is it safe to surmise that transfer slot fueling is critical for flame kernel development and general cylinder conditioning?

I found an interesting paper from Heywood:Early Flame Development and Burning Rates in Spark Ignition Engines and Their Cyclic Variability on JSTOR

This statement from Heywood for me is profound: "It also suggests that cycle by cycle variations in the position and growth rate of the flame kernel at very early times are the very cause of the cycle by cycle fluctuations in the pressure curves for spark ignition engines."