Mines got 4 or maybe 5!!! What? Please elaborate
I know for sure it has 4....I'm pretty sure they are all open...I would say .020( this is a guess ) but I think you have to drill and tap them if you want to plug them...Or I can use some epoxy....
Mainly, what must be understood is that because the fuel discharge nozzle connects the venturi to the main well, whatever the low pressure (vacuum) is in the venturi, it is also the pressure in the main well. The air bleed is in the carb air horn or somewhere else where it is exposed to essentially atmospheric pressure, which is higher than the venturi pressure. This pressure difference causes air from the air bleed to flow through the emulsion system into the main well and to the nozzle. The flow of air can have very high velocities, approaching sonic in some orifices. The airflow literally blows the fuel toward and through the nozzle. A larger main air bleed will admit more air to the emulsion system and that can increase or decrease fuel flow to the engine. The size, number and location of the other air holes in the emulsion system, the size of the main well flow area, the size of the nozzle and the specific pressure difference at the moment are the determining factors. The ratios of air volume to fuel volume to flow area, with the air volume's expansion with the venturi velocity induced pressure reduction being the key. The bubbles expand as the pressure drop increases with airflow. Suck on an empty balloon to experience the effect.
The fuel flow through the main jet is the result of the pressure difference between the atmospheric pressure in the float bowl and the venturi air velocity induced vacuum acting on the nozzle and the main well. The venturi vacuum in the well is reduced (the pressure is raised) by the "air leak" from the air bleed. This reduces the pressure difference that causes the flow through the main jet. If the air bleed were big enough, the pressure in the well would be the same as in the float bowl and no fuel would flow. Think about drinking through a soda straw with a hole in it above liquid level. Bigger hole, less soda. Suck harder, not much more soda. Big enough hole, no soda. This is the means by which the emulsion system can "lean it out on the top end". Incidentally, the vacuum that lifts water up a soda straw is in the most sensitive operating range for emulsion systems.
It is in the lowest range of throttle opening, at the start of main system flow, that the effect of adjusting the introduced emulsion air (and it's effect in increasing the main fuel flow) is most critical. Small changes can have large and sometimes unexpected or counter-intuitive consequences. The goal is to seamlessly blend the rising main flow with the declining idle/transition system fuel delivery to accomplish smooth engine operation during opening of the throttle in all conditions, whether from curb idle or any higher engine speed. The high speed and load mixture correction is usually easily accomplished, in comparison.
The vertical location of the bleeds entering the main well influences the fuel flow in the following ways.
1: Orifices above float level or between the well and the nozzle allow bled air to raise the pressure (reduce the vacuum) in the nozzle and above the fuel in the well. That delays the initial start of fuel flow from the nozzle to a higher air flow through the venturi and is used to control the point in the early throttle opening where the main starts.
2: Orifices at float level increase low range (early throttle opening) fuel flow by carrying fuel with the airflow to the nozzle.
3: Orifices below float level increase fuel flow by the effect of lowering the level of fuel in the well to the hole(s) admitting air. This is like raising the float level a similar amount (increases the effect of gravity in the pressure difference across the main jet) and also adds to the airflow carrying fuel to the nozzle. Locating the orifices at different vertical positions influences this effect’s progression.
4: The "emulsion holes" influence is greatest at low flows and the "main air bleed" has most influence at high flows.
In the first three cases above, once fuel flow is established it is greater than it would be with fewer or smaller holes. Visualize wind blowing spray off of the top of water waves. It doesn’t take much pressure difference to cause the velocity of the airflow through the bleed orifices to have significant velocity in the orifice, even approaching sonic (1100 F.P.S.) if the orifices are small. The phenomena of critical flow is what limits the total air flow through an orifice and allows tuning by changing bleed size.
Essentially, the emulsion effect will richen the low flow and the air bleed size, main well and nozzle restrictions will control the increase or reduction of high flow. Again, the desired air/fuel ratio is the primary purpose of the bleed system. "Improved emulsion" is an oxymoron if the modification of air bleeds to "improve emulsion" results in an incorrect air/fuel ratio in some range of engine operation. Correct proportioning of all the different bleeds (and, of course, the idle, transition and power circuits) will give the correct air/fuel ratios over the total range of speeds and loads and a flat air/fuel ratio characteristic at wide open throttle
They used to call the main air bleed an "air corrector" because its function is to correct for RPM dependent AF ratios. There is a window of HS bleed sizes that will work with a particular combo that will allow a fairly flat AF curve — out side that window the fuel curve will tend to go richer or leaner with increasing RPM. In your case it sounds like the main air bleed is too big.
The other aspect of emulsion is the actual emulsion hole configuration. Emulsion holes effect the lower end of the RPM band and have the most influence over your air mixture just as the main circuit kicks in. Higher in the RPM band the high speed bleed has much more influence. The stock Holley two-hole setup has proven to work very well over the years and after a bunch of experimenting with my four-hole blocks I wound up at the stock Holley configuration.
If you talk with Tuner on the Innovate site, he'll tell you about how so many "new and improved" billet carbs suffer from too much emulsion air. That is to say, high speed bleeds that are too big and emulsion holes that are too many. I happen to agree with him, and based on the limited info you provided I would hazard to say that that your carb suffers from a classic case of this "too much and too many" syndrome.
For your setup I would suggest that you go back to a two hole emulsion setup with the top, middle and lowest holes plugged; the second from top and second from bottom holes should be .028". For a high speed bleed you may want to be smaller than you currently are to flatten out the top of your fuel curve but cannot recommend a size not knowing where you are at now.
