here is a nice little post i found yesterday (have fun with this one)...
i think it hints at how the t-slot can act once the mains start.
are these all possible???
fuel always flows through the t-slot?
fuel flow tapers down some?
fuel flow stops?
fuel flow stops...but in some cases the pressure at the t-slot is so great air can enter and screw with the MAB pressure in the main well and therefore effect fuel flow to your booster...?
11-09-2011, 12:54 PM
shrinker
Registered User Join Date: Dec 2006
Location: Adelaide South Australia
Posts: 2,410
Fair enough Plato. So what i will do is ill post my reply to him, here it is.
Air flows through the HSAB and out into the main well via the emulsion bleeds. If there is an emulsion bleed located near the fuel level air can flow through this part of the system at very low CFM flow through the carby. There is a the Kill bleed also and its always conveying fuel vapors. Once the main jet is enough restriction to lower the fuel level in the well to expose the highest e-bleed air will flow freely through the system. This air beings even more fuel fumes with it, the engine combustion of those fumes is part of the AFR. Any time the pressure differential between the main well and the HSAB channel is enough to cause air to flow through that system the AFR will be affected. If there is not enough air to lift the liquid fuel to the booster height there will still be enough air to convey fumes.
As for the idle t-slot circuit it has to interact with the main jet. Many people have too large a main jet for correct interaction to the idle circuit. They have too large a main jet because the HSAB is too large creating a situation where air is taking up too much space in the main well fluid flow stream at high CFM flow values and the engine leans out so they install a larger main jet to compensate. That 'fixes' their issue at the top end but it makes the bottom end too rich, then they go and make the IFR smaller and discover that the crossover from t-slot to the mains has a lean hole in it, so they make the IAB smaller and then at high CFM the pressure at the t-slot in the throttle bore exceeds the pressure in the HSAB channel and fuel flow stops from the t-slot and air starts backflowing and enters the main well at the base where the IFR is and pop it goes lean. And it all started because the main jet was incorrectly sized.
The first thing that has to be right is the size of the main jet and the head of fuel above it. . ALL other jet settings depend upon the flow rate of the main jet.
