I want to test an HP 950 in place of the HP 750. My 750 is using 83/85 jets. What should I start with on this 950? Same? up size 2?

Start with the 2 sizes up but get ready to
run less
Adjust it for best MPH

That's a lot of jet for a "normal" tune on a 750........I'd start 78-86 on the 950 as a starting point IF you run a p/v if not, 86 squared..........what are the idle and hi bleeds.........

Which model # "HP 950"? The old 80496 w/ the 1.38" venturi (like the HP 750) or the new 80805 with the 1.60" venturi? Those two "950" carbs are way different.

The factory jetting for an 80496 is 78 square (power valves on both primary & secondary sides), FWIW.

The car is either wide open or idle. The car ran the best et and MPH staggered like that. The car runs out of wind at the big end of the track and I really just curious if my 950 will it up.

As for the bleed I never swapped them out, they are what holley screwed in there.

Run it with the stock jets. Almost every Holley carb I've ever used works pretty good with stock jets. The factory engineers know what they are doing when it comes to main circuit calibration.

Agreed, but too bad they aren't assembled by engineers and have seen em whacked out and wound not run for chit as they arrived. Good point Brad about the venturis(my bad)although the two 950'2 both small and larger venturis were close in jetting.........If you don't map out the WHOLE carb, it's guess work period.............