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I offer a simple comparison of the E-tubes I have on hand. Those with their first hole slightly above float level are grouped to the left. Holes higher up delay main circuit activation and those below float level lean fuel once fuel flow demand is great enough to allow air to pass through them. Those with holes slightly above float level will blow air across the fuel thereby atomizing it at the initiation of the main circuit operation. Note the F24 E-tube which was OEM for the 906 engines with 42mm main venturis; those engines needed all the help they could get to initiate main circuit operation.
Note F3 and F7 are the same except F3 has lower holes which is a leaning effect at high RPM where the High Speed Enrichment feature of the IDS carbs supplied fuel for that region of operation.
Easy to source and try, get some F26s and expect main and air correction jets to change as a result.
It could be that if the F26s helped but were deficient elsewhere where F3s were good then you could add some holes to a set of F3s above the fuel level line...
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One last carburetor topic: You say you have IDAs. I hope you are correct and don't have IDTPs. IDTs are essentially equal to IDAs but IDTPs are a bit deficient in their progression circuit operation as they were developed for use with 27mm main venturis. In either case you can make a simple modification that allows tuning the size of the idle air bleed jet. The idle circuit bleed jet operates much like the main circuit air correction jet; larger air jet and main circuit activation is delayed and top end is shortened and leaned, smaller jets have converse effect. So, smaller idle air bleeds (110s are in IDAs and 140s are in IDTPs) will extend and enrich progression/transition performance.
The 46IDAs for 906 engines used 80 idle air bleeds, 70 idle jets and 145 main air correction jets which imply a big effort to fuel the transition region of operation. Not an exact science this comparative info but interesting to consider.
