I was able to copy and paste the link you found. Seems like not many people really understand how to use them in tuning a carb, myself included. I have a couple of Holley carb books and they are hardly mentioned at all.
Can someone explain emulsion tuning?
- Thread starter hunt2elk
- Start date
33 IMP
Well-Known Member
- Local time
- 10:05 AM
- Joined
- Dec 21, 2017
- Messages
- 12,777
- Reaction score
- 20,771
- Location
- taxifornia,soon 2b Arizona.
That I can agree with! I have never seen a cogent explanation of what they do to the fuel curve, how much or where or when.
I have a quick fuel block in my ancient 850 dp, with changeable emulsion jets, but since i couldnt find out what they do, I left them alone. When I get some more laps on the car, further tuning will be done.
BB BELLA
Well-Known Member
and all this time i was putting pieces of copper wire in the holley metering block orifices to control mid range fuel, thought that was the only way!
Hunt2elk, nobody messes with them much. Unless you're a highly experienced dyno operator, or own your own track. Lots of trial and error.
There's an old performance shop guy/racer at the track, and he will always say 2x 2x 3x something something is the way to go.
I can't remember the numbers, and I run an old modified holley lol.
There's an old performance shop guy/racer at the track, and he will always say 2x 2x 3x something something is the way to go.
I can't remember the numbers, and I run an old modified holley lol.
Jeremiah
Well-Known Member
The emulsion package changes its function as the fuel level in the bowl drops and uncovers the emulsion jets. Think of the main well being filled with emulsified fuel/air mixture at cruise and then you go WOT, opening the primary side power valve and pulling enough air through the MAB to start moving fuel through the booster. The top emulsion bleed gets uncovered, eventually killing the transition circuit as the main jet and power valve start adding fuel to the main circuit.
That said all of my tuning is as stated in the other post. IFR, MAB, IAB, main jets, power vlave and PVRC.
That said all of my tuning is as stated in the other post. IFR, MAB, IAB, main jets, power vlave and PVRC.
Last edited:
383man
Well-Known Member
They are basically where the main air bleeds mix with the fuel. Its alot more to them but thats the function they do. And I agree as most said for basic normal to mild combo's you dont have to get crazy into them. All the older Holley's like my 850 are not adjustable as they have no jets in them. You have to go to billet metering blocks to get the ones with jets in the emulsion tubes. I can say on my mild combo's I rarely ever have to make any changes with them. And if you dont work alot with carbs its best to not fool with them without talking to a very good carb person. Ron
Dragon Slayer
Well-Known Member
Carter AFBs used them also on many (but not all) models. Normally the primary venturi main pickup tube would have the most 11-12 holes. Secondary just 3-4. As fuel drops at high speed in an AFB more holes uncovered by lowering fuel that allows more air to be pulled into the fuel stream before getting to the discharge port. They also usually have a hole drilled far at the top of the pickup tube to act as an anti-siphon also.
383man
Well-Known Member
Thats true as many older carbs in some of my older books have anti-siphon's listed in them and in many respects they look to do just what an air bleed does and it looks like many can act as both. Ron
Geoff 2
Well-Known Member
The OP is clearly asking about removable emulsion jets, NOT main jets. My best advice is not to touch them. There was a very good reason they were originally non-removable......
What I think he is asking is how does the position [ top, bottom ] of the E jets affect carb operation. Upper holes cause a leaner mixture at all rpms. Low holes cause richness at low rpms because there is a greater fuel reserve ready to be delivered to the booster.
What I think he is asking is how does the position [ top, bottom ] of the E jets affect carb operation. Upper holes cause a leaner mixture at all rpms. Low holes cause richness at low rpms because there is a greater fuel reserve ready to be delivered to the booster.
Dragon Slayer
Well-Known Member
I am not sure that is true. At least not on the Carter venturi. How rich or lean the quality of the mixture is depends on the fuel level in the tube. At higher rpm were the fuel level drops and more emulsion holes are uncovered results in more air mixed into the fuel and a leaner quality. The venturi pickup is an open bottom tube with much greater surface area than the main jet. Those extra holes are not introducing more fuel but changing the calibration as they become exposed. As the pressure differential is trying to extract fuel more air leaks on lowering fuel level results in less fuel pulled and more air. Calibrated to lean the mixture at WOT High RPM. No?
Similar threads
