Bruce ( Shrinker )

carby tuning techniques said
The camshaft profile greatly effects the vaporization of the fuel,especially in low load driving.There is potentially a large amount of vacuum generated as the intake valve lifts off the seat area and its this area where a lot of vaporization takes place.You can kill this area real quick when you change cam profile,speed of lift etc..
You can tan a plug on wide LSA cams real easy even at idle if you get the fueling correct.narrow lobe cams need a lot of comp and good fuel.
Fuel is such a key component to it all,the quality that is.
The inlet valve closing point in relation to piston speed will determine the first stage of compression,whether it is slow or fast.The energy that is added to the fuel molecules in the first stage is very critical.

If I'm correct in how I read that then different valve curtain areas would need a different lobe designs to create the vacuum necessary to maintain vacuum profile to suit the fuel being used in relation to piston speed and cylinder fill time.

I take it that low loads means Isothermal Compression and high loads are Adiabatic so how would you have to balance out those demands with intake closing and rpm ranges.

I remember Bruce saying this about it:

The time spent in isothermal compression is critical to the vaporization level of the chamber. When you close the intake valve earlier you increase the time of isothermal compression, thus the engine gains low down power, however the trade off is as you rev it faster the valve closing goes straight into adiabatic and the vaporization suffers and the engine looses power. What ever the temperature of the air in the chamber at the point where it crosses to adiabatic will be the temperature until it drops back out of adiabatic somewhere as the piston slows in the top half of the stroke.
So now can anyone see why I say what I keep saying?

Hint, if you decrease droplet size you will increase vaporization at all points especially in the zones where its inhibited by the type of compression
That’s what carby sizing does too. The whole intake system is a vital part of the vaporization.