I am running 80s on all 4 corners with Promaxx jettable plates and 64 in the center carb. On my AEM gauge, it reads mid 13s-14s at idle. On cruise in third gear it's mid 12s and on the freeway its mid 12s also. Number 7 plug is dark and fouling so I changed the drivers side rear jet to 78. At idle the gauge reads 16s now. At cruise and freeway it reads mid 13s-14s now. Should I put the jet back to 80 and fool around with the mixture screws or leave 78 in and fool around with the mixture screws? I don't like seeing it read 16s. The outboard screws are a tad bit more than 1/4 out. This is a new plug with some idle time.

I did get it to 14.7-15.3 at idle, part cruise mid 14s.

What did you change to get your current numbers?
The type of fuel also comes into play IE: ethanol or straight gasoline.
What does it show at WOT ?
Staggered jetting was not uncommon with 6 packs back in the day and I believe was recommended in the DC manuals.

The only thing I did was turn the center carb mixture screws out a tad bit. I forgot to check wot numbers. Straight 91 octane.

My last stock type six pack set up liked 1/4 to 1/3 a turnout from gently bottom on the idle mixtures screws on the outboard carbs and 1 to 1 1/2 turns out on the center carb mixture screws.
it like to cruise at light part throttle cruising under 2300 RPM between 14.3 to 15.3 AFR on Oregon 91 octane pump swill with no ethanol in it
Best, max, vacuum reading got the higher AFR at cruise RPM in 2nd or high gear with 29.5 tall tires and 4.10 gears between 1200 and 2400 RPM

Changing any main jet will not change your idle AFR. Idle and light cruise mixture is determined by idle mixture screw adjustment, idle air bleed size, idle fuel restriction, transfer put restriction. Have you removed the lead plugs in the baseplates of the end carbs to gain access to the idle mixture screws?
Doug

This guy did some nice work that I rarely see posted.

https://www.forabodiesonly.com/mopar/threads/mechanical-six-pack-idle-circuits.411329/