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Discussion Starter #1
I bought one second hand, hand only a few dyno pulls on it. I installed it and cannot get it to run. Mixture screws do nothing, I can get a rough idle by opening the butterfly's way way up. It's basically running on the transition slot. It's a 2 circuit although these can be 3 circuit.

I'm about to pull it down and go through it.

But looking at it I have an air bleed question.

It has 12 being 4 barrell, 3 circuit body.

Looking at the top down view below (not my carb I pulled picture from Holley website) mine has the exact same air bleed layout. That is outer most bleed is a solid blank. Next to it is another bleed then closer to the vent tube is whjat I understand to be the HSAB.

BUt, my understanding is that it's always idle air bleed is the outer most bleed then next to that, essentially in the middle is the intermediate bleed and then closest to the vent tube is the high Speed air bleed.

If this is the case why would the Idle air bleed have the solid and the intermediate not. Or on these FX series is the idle air bleed the one in the middle?

Thanks in advance

 

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If it was originally a three circuit carb and was converted to two circuit, the air bleed location changes for the idle air bleed and then the other one is blocked off. That's because the two circuit blocks have those circuits located differently.
 

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If yours is blue like the picture it's an alcohol carb, not gas. And the alcohol carbs are 2 circuit, why the outer bleeds are plugged.
 

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Discussion Starter #4
Mine is the red one, but it is a 2 circuit and yeah idle bleeds are moved inboard to the middle using the 2 circuit metering block. I have that figured out. Still idling pig rich but I have new air bleeds and IFR's on the way to start tuning it
 

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It's probably a 4700 2 circuit 1050. It needs the idle feeds lowered, body threaded for adjustable t-slot restrictions, emulsion adjusted, main air bleeds adjusted, and idle feed restriction lowered.
 

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It's probably a 4700 2 circuit 1050. It needs the idle feeds lowered, body threaded for adjustable t-slot restrictions, emulsion adjusted, main air bleeds adjusted, and idle feed restriction lowered.
Thanks a lot for your advice
 
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