I guess I'm confused ands need to read the OP again. It's rich at cruise and has a tip in issue. How is that fixed with jets or Tslot? That doesn't make sense to me, but I've been wrong more than right. If it stumbles on tip in, it's either like mentioned above that the pump shot is too small or he needs fuel enrichment from the PV sooner.
Or so it seems to me. But I'm wrong. A lot. When he gets it tuned I hope he tells us what fixed it.
After rereading the original post your correct on which part of the carb to work on, it isn't in the transition circuit at 2600 RPM
OP, try the power enrichment circuit first, power valve opening vacuum rating and maybe the power valve enrichment channel size also
"Cruising at 55 mph at 2600 rpm the afr is about 13.5. WOT the afr is about 12.5-13. The problem area is part throttle about 1/3 to 1/2 throttle it goes really lean"
It appears that the reference to 2,600RPM is for the cruise ratio. The lean issue is part throttle transition. Which suggests to me that any one of several different circuits could be the culprit, including the ones mentioned above. But the OP needs to identify the offending circuit to correct, although he may cover up the problem by fattening up another circuit as is often done with the accelerator pump.
I'll give a recent example similar to this that I dealt with. After fighting a slight, but noticeable tip-in lean spike for a while, I finally called ThumperDart. After a few questions he had me run a test or two which determined that my lean spike happened right before the point the boosters activated. He suggested that I switch the top emulsion jet with the plugged second one. What he wanted was to bring the main circuit in a bit sooner. That did it! Fattening up other circuits may have covered up that issue, but that usually causes other issues. So, it's important to know what the circuits are doing and when they are doing it.
