General Category > Quadrajet Carb Talk and Tips
Secondary main well air bleed tubes
novadude:
The inverted bleed tubes and emulsion holes deal did not work well for me when I tried it. Seemed like it would start rich and trend lean. I didn't enlarge the well like he recommends, so maybe that had something to do with it? This was with a 0.026" bleed in the tube (moved to the top of the airhorn - other end soldered shut, 0.024" emulsion holes)
77cruiser:
--- Quote from: 70GS455 on November 06, 2025, 06:36:15 AM ---You are correct in your thinking.
The 0.036" did not work for me. I had a post earlier where it kept going lean at high rpm. One thing to note is that I'm near 600 HP with my setup so in order to get there the air door has to be open as far as possible (1.240"), yet I'm still 2" of manifold vac at WOT at the top of the pull. So there is less sec venturi effect vac to pull fuel.
For my 7043240, I reduced them to 0.025" and got really close with CE rods before the engine swallowed a screw. Next I will try 0.022" (the Ebrock RPM comes with 0.020"). I also closed the lower end of the tube and added extra emulsion holes like Tuner suggests although I don't agree with all his recommendations..
There is really good info here: https://www.tapatalk.com/groups/racingfuelsystems/viewtopic.php?p=16572#p16572
See the pic in the link above
So I don't think the 0.036" will work with higher HP applications. Unless you can close the air door a lot and run really small tip sec rods ( which I don't have) .
--- End quote ---
Must have been you that I saw you had tested diff. size secondary bleeds.
70GS455:
--- Quote from: novadude on November 06, 2025, 07:12:16 AM ---The inverted bleed tubes and emulsion holes deal did not work well for me when I tried it. Seemed like it would start rich and trend lean. I didn't enlarge the well like he recommends, so maybe that had something to do with it? This was with a 0.026" bleed in the tube (moved to the top of the airhorn - other end soldered shut, 0.024" emulsion holes)
--- End quote ---
That was the approach that worked for me. I do not agree with enlarging the well. It seems that will reduce the effects of emulsion air, which I need at lower rpms to enrichen it. I had a 0.025" bleed at the top, lower end soldered shut, and only 2 of 0.026" emulsion holes at the bottom. I will note that the orifice that feeds the secondary poe well was left at 0.027". If you have seen the videos of fuel being pulled out of the POE holes you'll understand the relevance of that so maybe my extra fueling from there is different.
77cruiser:
--- Quote from: novadude on November 06, 2025, 07:12:16 AM ---The inverted bleed tubes and emulsion holes deal did not work well for me when I tried it. Seemed like it would start rich and trend lean. I didn't enlarge the well like he recommends, so maybe that had something to do with it? This was with a 0.026" bleed in the tube (moved to the top of the airhorn - other end soldered shut, 0.024" emulsion holes)
--- End quote ---
I kinda quit testing, I was trying to get serious about by logging AFR & RPM but it seemed to be a PITA with the Innovate stuff it seemed so finicky. I guess since I quit going to the track, & as long as it runs good & can still do a 300 ft. smokey burnout it's all good.
novadude:
--- Quote from: 70GS455 on November 06, 2025, 10:26:32 AM ---That was the approach that worked for me. I do not agree with enlarging the well. It seems that will reduce the effects of emulsion air, which I need at lower rpms to enrichen it. I had a 0.025" bleed at the top, lower end soldered shut, and only 2 of 0.026" emulsion holes at the bottom. I will note that the orifice that feeds the secondary poe well was left at 0.027". If you have seen the videos of fuel being pulled out of the POE holes you'll understand the relevance of that so maybe my extra fueling from there is different.
--- End quote ---
I may need to revisit this. I had the four (4) .024" holes in the tube (and maybe a little too high) and it seemed like it was doing wierd things to the fuel curve.
0.027" is pretty small for the well re-fill holes (even in many stock model carbs I've seen). I would guess that the POE fuel probably isn't much of a player after intial WOT?
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