Update.... finally got some time and weather to play with the carb. I pulled the carb, swapped in 78 air bleeds (stock 70), blasted some carb cleaner through the idle air bleed passages, even though the whole carb looks very clean inside and out. Swapped in another 6.5 power valve in case this one was acting up. Dropped the fuel level to 1/3 of the sight glass instead of 1/2. Tested this out, front mixture screws, still Had to be turned almost all the way in and when I did turn them all the way in The car didn’t stall so transfer slot must have been completely closed, I could turn the secondary Mixture screw in All the way and the car would die. Pulled the carb and closed up the secondary Butterfly to shut the transfer slots from just a hair over square to Just barely there. Fired it up again... so it’s idling way better, still shaky idle, and now I’ve got 1/2 turn out on secondary mixture screws and about 1 turn out on the fronts. Still can’t get idle less then 875 with the throttle screw all the way unscrewed so at this setup like primary transfer slot is completely closed (I checked when the carb was off).
initial timing is at 16 degrees btdc. I think my next step is to close up the secondary butterfly a bit more but that will reduce my secondary transfer slot to zero. Then I can open up my primary butterfly and hopefully get my idle to 800 rpm. I think I may need even bigger idle air bleeds as well probably like an 82. I wonder if the carb is originally intended for big cams with little vacuum at idle. I’m making between 15 and 16 vac At idle with my little 224 @ 0.050 cam. Let me know what you think.