Holley Carburetor Emulsion

[BLACK BART]

Hello everyone. I have a multi-part question, or multiple questions if you will, that I can't seem to find clear answers to regarding emulsion in a Holley carburetor.


1) What does going from say (3) .028" emulsion holes per side of the metering block to (4) or (5) emulsion holes with the same total area as the (3) original holes typically do to the fuel curve?

1) I think this just gives finer emulsion via smaller air bubbles spread out over a larger area.


2) What does increasing/decreasing the emulsion hole diameter do to the fuel curve?

2) I think this does the same as increasing/decreasing the high speed air bleed. Increasing size leans mixture/Decreasing size richens mixture.


3) What does having the emulsion holes higher or lower in the main well do to the fuel curve?

3) I have no clue on this one.


4) What happens when you have the emulsion holes at the top progressively larger than the ones at the bottom or the other way around?

4) I also have no clue on this one.


I know there are many knowledgeable carburetor guys that frequent this board and would appreciate some of your input on these questions. I'm sure many others would as well since this information is not as easily found as information on other carburetor circuits. I have found some very vague, ambiguous, or even hinted at information regarding these questions, so my answers above might reflect what I've found by being wrong. Will someone that knows this stuff please help us that don't so we may better understand our carburetors? Thanks, CJ

[aedcarburetors]

Blackbart in order for u to get thoses answers you really need to understand how the emulsion circuit works .. i type this on another thread a few days ago..............................

the emulsion well is agame of cat and mouse one chases the other.........the emulsion well is a smaller volume cavity whos fuel level initially is the same as the fuel level in your float bowl..... the emulsion well is filled through the emulsion hole pack........once the main circuit gets cracking fuel is pulled up the main well....a small percentace of fuel is also pulled into the well through the emulsion holes.and this cavitys fuel level starts to lower .. when the level drops below a emulsion hole the main well is also pulling in air through this hole now as well.........at the same time this is happening the mean head of fuel in the bowl is acting on the bottom emulsion holes filling back up the emulsion well .......the higher the fuel level the bigger the head of fuel the more the bottom holes fill up the well..conversly the lower the level....... the less a rate the emulsion well is filling up......this is why more emulsion holes doesnt neccessarily mean more emulsion ........ the more holes under the mean fuel level the less the emulsion wells fuel level will drop exposing less holes to air....... and therefore pulling in less air... the main air bleed ... booster hole size relative to jet sizee determins how hard the main well trys to pull in fuel from the emulsion well.......... if the effective booster hole size is the same size as the main jet......which is pretty common in a lot of alcohol carbs ........ then the well will not pull hard on the emulsion well... because the jet is feeding all the booster can pull...... the booster always has to be bigger than the main jet in order to get the emulsion circuit working efficiently.... playing with fuel pressure and float levels is critical ... not just for idle quality etc ...

its pretty hard to tell you exactly what combinations of emulsion packs will do because there are so many variables.... ie booster / venturii combinations... well size and taper.......taper of a well is one of the most criticle points of a carburetors emulsion capability ............ the taper... is from big at top to smaller at bottom ....... on a petrol carb this can range from 140 thou - 160thou over 1 inch .........to 160 - 180 thou over 1 inch in a dominator block with an idle tube down the guts ............ the taper helps the booster lift the fuel up the well.. imagine if u had a funnel and u turned it around and if u had big lips u could suck from the large megaphone shaped end .. applying a depression across that surface area..... the smaller end would more effectivly pull up liquid if submersed in it .... now if u turned it around and tried sucking on the little end u would need smaller lips yes.. but a bigger depression across the smaller area to lift liquid up ...............the taper also biases the main well w to pull in more fuel from the lower placed emulsion holes since the well tapers to the bottom and since the booster feed hole is bigger than the bottom of the well diameter it will pull in more from the bottom since at the top the well is closer to the booster feed hole size.......all this is designed in a combination so that the emulsion wells fuel level will lower ..depending on flow rates in the main well...which is determinde via booster/venturii signal..which is determined via RPM/displacement of engine

Ray
RayJE Carburetors
Brisbane,Australia



[/quote]

[rmcomprandy]

What you are asking could take a whole book of explanation...!

Quickly, (at the great risk of over-simplification), WHERE the air enters the fuel in the main well and what PERCENTAGE from top hole to bottom hole, (or reversed), will SHAPE the fuel curve.
The size of the HSB gives the definitive angle of the fuel curve, (tipping the top or the bottom), one way or the other linearly, (more up, more down without reguard for the shape).

[BLACK BART]

Ray, what you said makes perfect sense to me about the cat and mouse analogy. It had never entered my mind that the fuel from the main well fills the emulsion cavity through the emulsion holes and is kind of recirculated around. I was looking at it like this cavity was dry all the time which seem pretty silly to me now. You have already taught me something new.



May I assume the following scenarios to be generally true based on how you say emulsion works?


Two identical carburetors ran on the same engine with exception to vertical placement of the emulsion holes will emulsify the fuel at different points in the rpm range. The lower placed holes say in metering block (A) would give a richer overall mixture sooner than the the higher placed holes in metering block (B) since the upper emulsion holes are uncovered later in the rpm range due to well head pressure holding emulsion cavity fuel level at the same point because the bottom holes are the same size.


Two identical carburetors ran on the same engine with exception to sizing the emulsion holes small at top/big at bottom on one carburetor and big at top/small at bottom on the other will emulsify the fuel at different points in the rpm range. The bigger holes holes at bottom say in metering block (A) would give a richer overall mixture sooner than the the smaller holes at bottom in metering block (B) since the well head pressure can flow more fuel through a larger hole at the bottom keeping the emulsion cavity fuller.



Ray, I hope these questions make sense to you and are not too far out in left field for you to answer. My appologies in advance if they are, but I am just trying to learn something here. Thanks, CJ

[BLACK BART]

rmcomprandy, I know there is a lot to explain. It's hard for me to figure out how to even ask the questions. Speaking of books, do you know of any that explain stuff like this? I've not run across one yet in my quest for this information.

Your explanation may be oversimplified, but it does help me get my head wrapped around this stuff a little better. If you care to elaborate on what you said above or add to it that would be great. Thanks, CJ

[Troy Patterson]

I am responding generally, not specifically to anyone.

The greatest advice I could offer with regard to carburetor function is that it is that you must see it as an extension of the engine, and that the engine is an extension of the carburetor.

There is no such thing as a short cut to understanding and application of principals.

Understanding the "system" is the "black art" of carburetor science. I personally learned more about engine function and operation through my carburetor work. I came to understand more about cams, exhaust and so forth through the carb than all the theoretical / academic / car magazine articles combined - but they all helped.

I'd be surprised if any of the carb "experts" will give you what they have spent decades learning at great cost in time and money.

Where in central Cal are you?

Troy

[BLACK BART]

Hello Troy, you were one I was hoping would comment on some of these questions. I do realize that there are no short cuts that will give me all the answers in just a few moments, but any information given on this board is a short cut in some capacity. I just figured that there would be someone here generous enough to point me in the right direction so that it would not take me decades to learn this stuff.

Something Darin Morgan said in a post to someone pissed off at him for sharing information comes to mind here. He roughly said that unless you physically go out and learn without the help of books, the internet, or anyone else, you are taking some sort of short cut by using information that you did not gather.

I know that I will still have to experiment because every combination is different and has different requirements. I'm not trying to get around experimenting to find the proper tune, I enjoy that part of the hobby. Troy, I also have learned much about other engine functions as a result of trying to tune the carburetor on my car. As far as the system you speak of, I tried to phrase my questions so that there was only one variable taken into consideration at a time. I understand that the whole system has to work as one and that any single change will make other things change as well.


Quote:
Troy Patterson,"I'd be surprised if any of the carb "experts" will give you what they have spent decades learning at great cost in time and money. "


It is unfortunate that some do in fact feel this way. I understand that proprietary information can't be freely given out, but it seems like half of the carburetors being sold now have tunable metering blocks. I would think that how to tune them would be somewhat mainstream information by now. Troy, I am not trying to single you out or upset you with what I am saying about the quote above. You do share information here and I thank you for that. CJ

[aedcarburetors]

CJ

your basically on the right track ....... just remember that the main well is tapered and that the further an emulsion hole is placed down the well with the same jet and booster size the more the booster trys to pull in fuel from the emulsion hole lowering the emulsion wells level

on 2 x 4 (Dominator) small block comp engines with 4 fuel bowls supplying around 250HP per bowl . you will find a tightly packed emulsion pack up high...as well as a hole placed low right down near the bottom of the well to speed up the rate of fall of the emulsion well..........needle&seat selection is important........you need to choose a needle and seat size / pressure that is as close as u can get to your engines fuel needs...........thinking that more is better which makes guys put 130 thou needle/ seats and running 7 psi in there 750 DP on an engine making 400HP totally screws up the carbs metering. a 97 tho holley needle/seat with .250 float drop at 7 psi will supply enough fuel to feed around 250HP per bowl on petrol...........110 thou at .250 float drop and 7 psi will supply around 325HP per bowl.......

CJ i have no problem sharing any info with anyone ...... you never stop learning .........plus in this game u cant afford to ..........

My old man told me this one time ..."What you discovered yesterday........ somebody discovered it the day before and someone else will discover it tomorrow"

Guys like Darin and others on here are constantly developing and moving ahead so have no problems sharing info.

Ray
RayJE Carburetors
Brisbane, Australia

[BLACK BART]

Thanks Ray, it will take a little bit for me to digest this and think about it. I do have more questions for you if you don't mind, but I want to try and think them through really well before I ask them so that I don't waste your time. I just needed a place to start from since I cannot find any information on this stuff. I would like to thank all of you that are helping me with this. CJ

[Troy Patterson]

Quote:
Troy Patterson,"I'd be surprised if any of the carb "experts" will give you what they have spent decades learning at great cost in time and money. "

It is unfortunate that some do in fact feel this way. I understand that proprietary information can't be freely given out, but it seems like half of the carburetors being sold now have tunable metering blocks. I would think that how to tune them would be somewhat mainstream information by now. Troy, I am not trying to single you out or upset you with what I am saying about the quote above. You do share information here and I thank you for that. CJ

Have you looked into the various Holley and Demon tuning books?

Knowledge is money - money spent to learn it. When you've invested years of your life, and tens of thousands of dollars out of your own pocket on developing your knowledge in some area, you understand better. I've noticed none of the other carburetor guru's (with the exception of aedcarburetors) have volunteered said info.

Read up and good luck. You can accelerate your own learning curve by making an investment - purchasing a "developed" carburetor from a carb "guru," then you'll get lot's of advice and help.

Troy Patterson TMPCarbs.net TMP Carbs

[Tuner]

This may shed some light on the subject.
http://www.innovatemotorsports.com/foru ... php?t=3371

The wells in the original Holley parts are tapered because the injection molding process requires a tapered shape on the pin that forms the cavity so it will extract from the part when the die opens.

[Shrinker]

GiDay Tuner.

[BLACK BART]

Thanks Tuner, that should help fill in some of the pieces in the puzzle. I've checked out the Innovate web site in the past and liked the forums there, but never thought to look there for this information now. Thanks again, CJ

[aedcarburetors]

This may shed some light on the subject.
http://www.innovatemotorsports.com/foru ... php?t=3371

The wells in the original Holley parts are tapered because the injection molding process requires a tapered shape on the pin that forms the cavity so it will extract from the part when the die opens.

This may be true tuner... are you saying that the main reason the main well in a holley block is tapered is because of a manufacturing technique. Isnt it possible to have a parralell sided hole using a Plug/Mold ...... why do they still run a taper in there billet metering blocks ....i would have thought if they wanted a straight paralell well they could have molded them that way easily .... im no expert in casting or even carburation for that mater... still learning

if you ran a drill down the well of a metering block with the same diameter as the large taper diameter and drilled all the way to the bottom of the well so its all one size .... just watch your metering go out the window.......
Ray
RayJE Carburetors
Brisbane,Australia

it would be great to hear from guys like Dan Smith , Patrick James and Phil Beshear with there thoughts on carburetor emulsion.....

[BLACK BART]

Hey Ray, this is one area where I may actually be able to give back to you a little bit. I used to work at a place that made carbon fiber tubes by wraping resin saturated carbon fiber tape around a mandrel. After the curing process, we had to pull the mandrels out of the tube with a mechanical puller. We tried a parallel mandrel for a special small diameter tube of about .150" ID and it was a disaster. No mater what we lubed the mandrel with it would not come out.

I know that the zinc material is way different than carbon fiber, but I would think that the principals would still be the same. The tubes we made were about 36" and had about .003"-.006" taper over the length, which is way longer than the main well in a Holley metering block. I think that the length, diameter, material, and tooling will all have a lot to do with the amount of taper needed if any. In other words if you have a short large diameter hole in a material not prone to stick to a mold pin or mandrel, you may not need any taper at all. I know that this is just speculation on my part where the metering blocks are concerned, but I wanted to share some of my experiences with you that may be relevant in a round about way. Thanks, CJ