Power Valve Selection

1/2 the idle vacuum in gear works. The PV should not be the first thing that comes in to add fuel, you have the accelerator pump and squirters that can be adjusted with the pump cam. The PV should come in after that.

The 750 double pumper on the 340 in my Duster came with a 6.5 PV, that’s a pretty standard off the shelf PV. If you have to double that, that should tell you something. My 340 runs 9-10 for idle vacuum, the 6.5 was too early. I run a 5.5 now, with 68 jets and 31 pump nozzles.

The fact that the OP his running really small primary jets and a PV that opens early should be an indication that things aren’t right.