[lippy]

Something else may be going on here. The changes you mentioned are radical. I change my jets in two-size increments at first and then one-size increments.

FYI, my carb is approximately an 850 and I have a 487 FE, and I run 74 jets primary and secondary, with 7.5 power valves and size 57 PVCRs.

Is your spike to 16 just a brief transition, or does it persist? Depending on the situation, I sometimes get a brief lean or rich condition, but it is always brief (a spike) and corrects itself quickly. That shouldn't be something to worry about too much.

Also keep in mind that your LSABs and HSABs have only a small effect on mixture (remember you are changing the air component and not the fuel component) but they do impact when the circuits are engaged. For example, smaller HSABs will make the cruise and WOT mixture slightly richer, but importantly they will engage the main circuits more quickly.