Pierce Manifolds also has a wide selection of emulstion tubes. I also tried the F80s, but they provided too much fuel at the transition point. When mixture enrichment for slight accelerations is needed, the fuel reserve in the emulsion well must be increased - this is obtained by fitting a tube having a small outside diameter, orificates located predominately in the lower portion of the tube and larger size air bleed to prevent excessive mixture richness at high rpm."Īs you will see on the web page under part group 61440, the F66 emulsion tube have three sets of 4 holes of larger diameter, located lower on the tube when compared to the F50 emulsion tubes. 61440.181 Emulsion Tube F3 61440.182 Emulsion Tube F5 61440.211 Emulsion Tube F6 61440.226 Emulsion Tube F7 61440.213 Emulsion Tube F24 61440. For mixture weakening at low rpm or during slight accelerations use tubes with orifices on top. The nice thing about the tubes in the IDF and some other carbs is they. The theory here will apply to other carbs as well. I will be talking about the tubes found in the Weber IDF carbs that are most commonly used. This is a tube found in a carburetor that mixes fuel and air for the main circuit. "For mixture enrichment at low rpm or during slight acceleration use tubes without orifices at top (note that the F50 emulsion tubes have larger orifices at the top portion). The definition of the word emulsion is to mix. I also read the Weber Tuning manual when I went to tuning the DCOEs. Read the stuff about the role of the emulsion tubes and how it describes their selection. This web page from the Carburatori Weber site provides some information I found useful in setting up the carb. Driveability was as good as the 32/36, but pulled with more conviction and a breathed better at upper end. An F2 was designed before an F7, and an F7 was before an F8, F9, etc. The above combinition is on a relatively stock '76 2002 engine (Tii exhaust, electronic ignition) an gave no stumble, no hesitation and AFR readings of 13-14.5 over 900-5500 RPM in variousmloading conditions. The emulsion tube ing system is in order of development. I should note that the 38/38 I am running has a 250 Needle Valve (not a 200 as noted by the ealier poster), 60 Pump Jet (slightly smaller than stock size) and 35 Pump Bleed (slightly larger size). As you can see I took a different route in dialing this carb. We are at 600 feet above sea level here in Fort Worth. I experimented with several emulsion tubes on my 38/38 (not a cheap proposition), and the F66 with its lower drilled holes eliminated the transition phase lean out as measured with an WBO2 sensor. One way that I found to improve the lean-out in the transition phase was to change from an F50 to F66 emulsion tubes.
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