Three emulsions better than two?

[jmarkaudio]

Part of this we have to look at is what booster does it have? Annulars atomize fuel better, so likely they need less overall emulsion. With downlegs are they stepped, what size hole thru the center and what size fuel leg does it have? Those will all impact the atomization of the fuel leaving the booster and better atomization leads to better vaporization and distribution. So if you have a stock non stepped downleg with the leg too big you may see a performance improvement by adding emulsion in a specific RPM range, and if that's the carb and combo you have to live with so be it. The factories put tabs on downlegs to manipulate distribution, so while it may not be optimum for all RPM ranges you may need a little more than whats ideal for the fuel curve of that combo. And last, you may help your engine performance by adding emulsion, but is it because you are bandaiding another problem? Incorrect plug heat range, incorrect timing curve, issues with the ignition system somewhere, poor induction distribution. To add a pun all parts matter...

[Right hand drive]

[Right hand drive]

Sorry, confused by the band-aid hypothesis. If something is done to alter fuel delivery quality to improve performance even with an aspect of the engine sub par, wouldn’t it still improve performance once that sub par aspect has been rectified? Or are you talking of an alteration of a/f ratio as a band-aid by the emulsion that would need adjusting when one or more of the deficiencies you mentioned are resolved?

[jmarkaudio]

It's a bandaid because the emulsion is actually an air bleed system designed to correct the fuel curve a booster creates, not to emulsify fuel. when you get excessive with emulsion you disturb the fuel curve somewhere in the throttle opening, and also can create inconsistencies in delivery of the fuel. While you might get power gains in specific RPM or load points, it will disturb it somewhere else. On a max effort engine that operates in a limited RPM range you do what you can to maximize power in that range. On a street engine that operates over a wider range that is not ideal. Look at the factory Holleys that were made, they didn't resort to massive emulsion, they used tabbed boosters to manipulate distribution to improve efficiency and performance.

[Right hand drive]

Agree with emulsion bleeds not pre atomizing or magically creating a more powerful fuel in the main well as I stated above.

What I meant by ‘fuel delivery quality to improve performance ’ is that going from .028, blank, .028, blank, blank and .028, blank, blank, blank, .028 to emulsion of .025, blank, .025, blank, .025 all with 28 mab barely changed the AFR yet noticeably helped performance on the 750 Demon. Acceleration is stronger. I was hypothesizing that more and smaller air bubbles introduced to main well had a positive effect on the ability of the booster to draw fuel from the main well and atomize that fuel better at the booster? I might be wrong but it seemed the correction to fuel curve by the different emulsion combinations were similar yet ultimately distribution was better with x3 smaller. Dyno and track testing will be done to gauge the output difference of the emulsion combinations but my theoretical mind is seeking the answers of why a performance change for now. Knowledge is power in more ways than one in this game. Of note the 850 downleg Demon the x3 v x2 emulsion setup experiment it was hard to detect a performance change. I am sure there would be an output difference but it would need dyno runs to pinpoint.

Thanks for taking the time to answer my questions.

[Right hand drive]

[Right hand drive]

It’s understood that air bleeds and emulsion work together to correct a/f ratio at increasing throttle angle. To get the best performance out of the engine combo the carburetor is on the air bleed system needs to be tailored to that engine. However, would air bleed and emulsion sizes - number and height, be influenced more by carby cfm or engine combo under it to be within a certain ranges?

I ask this question because it seem all cfm Demon gas 4150 style carbs use the same metering block of .031” block .031” block .031” emulsion with the one exception 850 downleg having .033” at the bottom (boost and alcohol are different). This is true of their Speed, Mighty and Race Demo when in production. Someone may correct me but from what I have read Holley Ultra HP/XP are similar in that all cfm have .029”, .029”, .029”, block, .029”. Quickfuel I am not sure about their use of emulsion across cfm ranges. We would all agree this is a lot of emulsion but why the same for all cfm in the same brand? Nothing but cost saving?
But does it also apply to tuning our own combo’s. If x3 .025” emulsion works best for us in our 750cfm will it be close to the best emulsion setup In an 850 on the same engine? Would x2 .028” emulsion on an 850cfm be transferable to a 750 or even 650 on the same engine. I could see that MAB and IAB may need to be different.

Do custom carburetor builders such as Pro guys that do Systems have a favorite emulsion packages across their range like Holley and Demon or truly customized emulsion packages dependent on engine combo info supplied by the customer?

I never really explained why the still pic of the carby in operation above. It was to reinforce that excess emulsion and MAB makes the fuel a bit blobby than finely ‘emulsified’ as most on this forum believe. It looks randomly blobby to me. That is a Mighty Demon 750cfm that has the x3 .031” emulsion and MAB of .039”.

[bigblockmark]

I built 3 engines for a customer/friend All were different combos. He bought 3 Pro systems carbs custom built for each engine. He showed me the build sheets for them. All 3 carbs were identical calibrations including emulsions, air bleeds and jetting.

[Right hand drive]

[hysteric]

Interesting discussion.

In Obert's book "Internal combustion engines and air pollution" he says on page 396 about air bleeding:

"As the suction increases, the influence of the viscosity diminishes and therefore the air entering the nozzle decreases the flow rate of the liquid."



Some thing to think about in that light from Shrinker:

"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."

Maybe too much emulsion going on