I have a rebuilt 12asp engine with a holley 4160 racing beat carb with 56 primaries. Engine runs great but when opened up it starts breaking up at about 5k and the afr number sets at 11.8. Firstly if my secondaries aren't opening (used the paper clip trick and it moved but not to the point of the vacuum fully opening) why would it be reading richer? Idle sits about 12.5-13.3. Cruising about 14ish. Went thru the secondaries and replaced the plastic shaft bushings that were tired thinking it was leaking vac there and sprayed out the bleeds and such..... ideas?

 

i don't know how the Holley secondaries work, but aren't there different springs or something?

as air flow goes up, the engine will pull more fuel, so since air flow is WAY up through the carb, its not surprising that its doing something weird, and it being rich is kind of expected. (pressure difference between the venturi and the top of the float bowl would be really high)

 

I mixed and swapped my two carbs just last night.... one stock port holley setup and a Bridgeport holley setup..... here's where it got me......