Quote:
Originally Posted by priobe
Gaz64,
Have you tried using this chart for your setup?
I dont believe this will adapt to my configuration. I think the idle circuit and the mains have something to do with which tube to use.
Now does the fuel flow from with in the tube or from the outter well of the tube.
Also, the higher the holes on the tube, does this mean that you will have a leaner mixture at the lower portion of the RPM when the Etube starts to function?
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I run an F2 in my V8 and an F15 in my little Datsun.
My understanding is the main well has liquid fuel in it prior to main system startup,
the inside of the emulsion tube to just below the lowest holes will have liquid fuel from this lowest point up to the float level.
The volume in the well is dictated by the outside and inside diameters of the tube.
Thick tube high holes - lean; thin tube low holes only - rich.
At the onset of main system startup, dictated by choke size versus cylinder displacement versus air corrector diameter, the bleed air admitted to the inside of the tube blasts through the fluid and to the auxilary nozzle to satisfy the negative depression created by the induction stroke.
As the engine speed increases the fluid level drops exposing each row of holes and leaning the mixture.
A fixed choke carburetor needs a form of correction to keep the A/F ratio consistent across the useable rpm band.
The A/F ratio would go from say 14:1 to "who knows" how rich without an emulsion tube/air corrector prior to the nozzle.
High holes would be leaner at startup, low holes only would be rich.
As stated from "How to build and power tune Weber and Dellorto DCOE & DHLA Carburetors:
"The following shows the Weber listing going rich to lean or large cylinder capacity to small cylinder capacity:
F7, F8, F2, F11, F16, F15, F9"
Of course they are many other tubes out there and some others including members here have experimented modifying existing tubes to their liking.
It's all about getting the engine cleanly onto the main system with the minimum amount of extra fuel from the accelerator pump.
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