That’s a Rochester B. You could try a couple things before you get your vac gauge. Turn the idle screw in and gently bottom it out. Turn back out 1.5 turns. That just gives a baseline to work from.
If the engine will run and idle, even if it’s rough, you can hunt for vacuum leaks by spraying something flammable at various places. Carb base gasket, intake manifold gasket, etc. if the idle smooths out or picks up, that place is leaking vacuum and needs addressed. In other words, it’s pulling the spray in through a leak in that area.
Some folks do the same thing with an unlit propane torch.
Well i got a vac gauge. Heres a vid of it at idle. (i dont have a tach)
https://www.youtube.com/shorts/ujJn-i8XXyYI tried the ether spray method, but got no discernible reaction by spraying it at intake ports, under carb, on carb gasket, on carb, all around the carb. And when i would spray a quick squirt into the air filter, the engine would die or nearly die.
