When adjusting air bleeds motor is changing trying to keep idle low

Also elevation is at 4000

The surging you are seeing should be able to be tuned out with the mixture screws and the proper idle speed screw setting

Thank u for your help

Good luck. Once you get it dialed in you should have a good combo.

Can you be clear on what model 750 carbs your using? Are they the Holley hp 750 supercharger carb as was stated in mild thunders post or are they 4779-? This can change things up a bit.

Btw the surging at idle is common even on Mercury hi perf supercharged engines. You can calm it down some with tuning as MT stated but not uncommon to have a little lope even with that cam or any cam as far as that goes.