just bought an 81 Doba w/slant 6.

I want to disable the airpump, and it runs the a/c compressor (which works BTW), so can I route a belt around this? It looks like there's no adjustment if I remove the airpump. Didn't previous years not have the airpump? Do I need to change the whole pulley assembly?

Also, how do you adjust the idle mixture (where's the screw) and idle speed. It's a single barrel carb. What is the earliest 1 barrel carb that I can use w/o having so many hoses and stuff sucking off it?

To ditch the smog pump on my '84 D100, I picked up an idler pulley and made a bracket for it. The bracket is adjustable so I can tension the AC compressor belt.

For a 1bbl, I like the '68-'73 Holley 1920.
Your best option is upgrading to a Super Six 2 bbl using a Carter BBD.
My D100 had the original Holley 1bbl on it and got 18mpg@65mph. Going to a BBD, along with a '76 D150 head pipe (no Cats), got it up to 20mpg@65mph.

Thanks so much!! Appreciate the tips!!