The jets do not influence the idle circuit at all. Changing the jets will not change the idle air fuel ratio.
The idle circuit is completely separate from the main circuit (jets). If you look at the bottom of the throttle bores, you will see a little slot (B in picture) in the throttle bore that crosses over the edge of the throttle plate when it is closed, this is the idle transfer passage. You will also see a small hole (A in picture) in the bore below the throttle plates; this is the idle discharge hole.
It is important to note that the idle circuit only functions during conditions of low throttle settings (nearly closed). When the throttle position is opened enough to provide sufficient airflow velocity at the venturi boosters, to promote fuel flow, the carb transitions from the idle circuit to the main circuit (jets).
Depending on which carbs you have, you may have either two idle mixture screws (most common) or you might have four corner idle mixture screws. Opening these screws (needle valves) only adds more fuel while at idle. Making adjustments to the idle does NOT change the air fuel ratio. It is probable, that you have carbs that were not originally intended for use in a dual quad setup and that your engine is already getting too much fuel at idle. The only way to change the air fuel ratio at idle is to alter the idle feed restrictions.
Is the popping from the passenger side coming from the exhaust? Do your carbs have 1:1 linkage or are they progressive linkage where the primaries open before the secondaries? IMHO, if not already, you should adjust your linkage to have a 1:1 opening ratio. Though some like the progressive linkage, I believe that it causes cylinders to operate under different conditions until WOT even though all share a common plenum. You may also find that you will end up with different size jets over each port to fine tune individual cylinder air fuel ratio.
I highly recommend Super Tuning and Modifying Holley Carburetors by Dave Emanuel to get you going.
http://www.amazon.com/Holley-Carburetors-Dave-Emanuel/dp/1884089283Regards,
Joe
From
http://www.crankshaftcoalition.com/wiki/Holley_4150/4160_tuning(A) Screw holes-
Four total, one in each corner used to fasten float bowl assembly/metering block to main body
(B) Idle downleg-
This passageway feeds fuel to both the idle discharge port and the idle transfer slot.
(C) Idle well-
Fuel from this well travels to the top of the metering block, then turns 180 degrees and mixes with air from the idle air bleed into the circuit.
(D) Accelerator pump passage-
This transfers fuel from the accelerator pump to the outlet nozzle.
(E) High-speed air bleed-
Air from the high-speed bleed enters the metering block here to be mixed with the fuel as it climbs the emulsion tube.
(F) Passage to booster-
This channel transfers fuel from the main well to the booster
(G) Ported vacuum passage-
This connects the ported vacuum source in the throttle body to the outlet where this can be routed to a source like vacuum advance.
(H) Parallel air well-
Air is introduced into the main well through these two holes.
(I) Main well-
Fuel collects here after passing through the main jet.
(J) Power valve port/channel restriction orifices-
This is where the power valve is located. The two small holes are the power valve channel restrictors (PVCR) that determine the amount of fuel added to the main metering circuit when the power valve opens. This valve determines when additional fuel is added to the main circuit.
(K) Idle restriction channel-
Fuel from the main circuit passes through this short channel and through a small brass restrictor (L) that acts as the idle circuit jet.
(M) Idle transfer slot discharge-
Idle fuel exits the metering block to deliver fuel to the transfer slot.
(N) Idle fuel discharge port-
Idle fuel exits the metering block and enters the carburetor main body for carb idle fuel below the throttle blades.
(O) Dowel pins-
Two pins locate the metering block on the carburetor main body.
