Afb carb

How to fine tune metering rods? Power piston springs? i will start with stock settings.

tune the "cruise" step with an LM1 (best) AF gauge & plug readings on fresh plug(s) & do that by going out on the interstate & pull over & sub in some new plugs & unhook the accel pump linkage & ease back on the road & go 10 miles & shut if off at speed/shift into neutral & coast to the side of the road & pull em & see how they look. Wallace racing has good plug reading pics. On the "power" step ET time slips or AF ratio gauge. On the springs hook a vacuum gauge to manifold vacuum & note idle vacuum and cruise vacuum range & I think you want the springs to come in no higher maybe 2" lower than idle vacuum. I'm rusty on some of this but this might get you started. I'm assuming you have a AFB strip kit or an eddy strip kit.

Thanks

You can measure the size of the different steps on the metering rods and then decide if you want the part throttle cruise richer or leaner, same thing at WOT the bottom small size step You compare your rod sizes and then decide if you want to go richer, smaller steps, or larger with thicker step rods
As far as the springs if it ain't broken don't fix it, in other words if it drives alright now work on the mixture first at part throttle and then at wide open throttle and then if you want, look at changing those springs. At W.O.T. you secondary jets come into play also if it is good at part throttle cruise and lean at WOT change the secondary jets up one size first and test it agian
Which carb, stock or replacement Hi Po or smog carb.
What motor and how much different is it from stock now?
Many things influence the carb., unlike the new cars with EFI

If you don't have these already, they are helpful as reference material.

- EM

This may be helpful as well although its more for service tuning than performance tuning.
The New AFB Carburetor Chrysler Service Ref. Booklet 121

In this one they describe how the systems work.
MTSC booklet 66-5 Carburetor Fundamentals p.9 is begining of the step up rods and main jets.

And if you hunt around on Edelbrocks' website, there is a chart showing various combos. Here's the one. You'll have to decide how applicable it may be to your carb, but the idea will be similar.
http://www.edelbrock.com/automotive/misc/tech-center/install/1000/1404_manual.pdf