Goody, with the rods, there is a power and a cruise step. WIth each jet, a bunch of rods can be used to get what you want. I use a vernier caliper to measure the rods' sections, and go "more" or "less" to get the curve where I want it. With a 3900 stall and 3.91s, you should be (in my opinion anyway) concentrating on the secondary air door and the power step of the rods. I'm not a fan of the "keep going up in squirtors" concept. Because when ever I did that, the plugs looked cruddy quickly, no to mention gas milage. In regard to your comment about "feeding it to the engine", that's backwards. A carb works by reaction. reaction to the pull from the intake, reaction to altitude and air pressure, reaction to G forces and inertia, reaction to air flowing thru the venturi. You dont tell it what it wants, it tells you. I "found" .2 from carefully tuning the accelerator pumps on my Holley DP. With careful tuning, i went from 4.30s and a 1.62 best 60' to a 1.65 best with 3.91s and no other changes. Same convertor, and a 3400lbs Cuda. The 4.30s made me not have to sweat the details. The los of .4 when I originally did the swap made me re-examine everything from burnout and tire pressure to timing and carb. By far the biggest gains came from the first 60' tuning the carb. I had 37s and a more aggresive cam in teh primary side. I ended up with the stock cam and 31s in it. Leaner is more power. The trick can be making it not detonate when it's lean. But the carb will tell you what it wants. I know 440s running that same carb that never had to up the squirtors. For a first step. I'd go back to the factory squitor size, keep the quickest hole, and try to get the secondary plate to open fast enough that it bogs. Then start to slow the openning down. Also keep in mind, the secondary jets dont have a rod, but you can jet them up and down too.