What you're going to find is that on a holley the circuits all stack up to be the final AFR. For the track it's pretty easy to tune for the fastest tune at WOT and you're getting there.

You can easily use the main jets to get the best ET, but a lot of street cruising is done mostly on gas mix coming out of the transition slot. This mix is regulated by the Idle Feed Restrictions (IFRs) which are only screw in jets on fancy metering blocks. The gas from these holes is emulsified and mixed with air from the low speed or idle air bleeds. On a race carb they will often be too rich for cruising without fouling your plugs. The way to tune this is to get the IFR size close either by sticking little Vs of wire (guitar string is cheap and .xx" exact) or if you're lucky with jets, or you can drill & tap make jets if you're handy. Once you're close you can fine tune with the air bleeds.

Watch out- when you tune the T-slots with the IFRs and idle bleeds you change the AFR of your whole idle system- which includes the four corner idle screws. These screws don't actually control the air/fuel ratio, thats the job of the IFRs and the air bleeds. They only control HOW mUCh of the mix drips/is pulled out of the idle discharge ports (little holes in venturis below butterflies).

I've found on racy holleys that I run on the street that the 4 idle screws can be a good indicator of how close the IFR/air bleed tune is. If you idle with all four screws out 3/4 turn then the idle system is too fat. Lean out those IFRs until you need to use 1 1/2 turns out on those idle screws. That should get you close to a nice lean tune for humming along just cracking the throttles.

Once you got that goin good move to the primary jets. You want a decently lean cruise on those too- this is where a power valve comes into play. On a chilled out highway speed trip you will probably get the throttles cracked open enough to use the primary main jets. The idea is to get them where it is lean but doesn't surge. If you drop the vacuum with more throttle it should start to get a little too lean and the primary Power Valve should open up and save the day with just the right amount of extra fuel. Of course the two holes under the PV (Power Valve Channel Restrictions) are another set of usually not tunable holes (a guess by holley at what kind of chevy 350 motor you have) so you can either get out the wires again or just get it as happy as possible.

So now you have the whole idle system and front 1/2 of the carb dialed in for razor sharp cruising and even a little economy. Fill in the holes with a little accellerator pump cam and jet selection and we're almost up to where you started- secondary jetting and power valve. A secondary power valve can help with extra fuel at WOT but it's not worth the risk and trouble- at the big end your high RPM could pull enough vac to shut the PV off and the motor will go lean. Not good. So skip the rear PV and just jet for ET/MPH and you're done.

Then check your plugs and decide if your fuel distribution sucks bad enough you can start all over.

Ha! Have fun- a carb is always a compromize but you can get them dialed in pretty darn well if you're willing to dig in a little and second guess the 'non adjustable' circuits. Jet changes alone usually won't get you there unless you only care about WOT