Setting up a Holley 390cfm vac secondaries on a 3.5

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Setting up a Holley 390cfm vac secondaries on a 3.5

Post by SpringV8 » Tue Aug 01, 2017 8:32 pm

I am adjusting a Holley 390cfm 4150 on a 3.5l
Engine is well, ignition is set to 5° advance at idle and carb is:
Main 57 jet
Fuel level OK
Power Valve 6.5
Vac at idle 15HG
AFR at idle 12,5AFR
Disabled secondaries
Disabled acceleration pump

My issue:
When I roll down the street with 60mph on a level street in 5th gear the wideband shows 12.5AFR. fine.
A little bit - 2mm on the pedal - more gas --> it accelerates AFR is still at 12.5. A bit more gas an the AFR will drop to 10.5 and stay there until I press the pedal a bit more - reving to 2500 then it goes leaner to 12.5 and you feel the car speeds up now...

Which jet system is dropping the AFR to 10.5 means make it so fat at this low, low throttle?
If I press the throttle to WOT - slow or fast you do not feel anything.
Only when I press and keep the pedal 4-5 mm open.

Any advice ?

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