78 high cold idle rpm

[76shuvlinoff]

I brought an all original low mile 78 Big 10 home a week ago, still learning it's quirks.
250 straight six, factory carb. My concern today is what I think is high cold idle rpm. I get in, give the accelerator a slight tap hit the key and it fires right off but the idle is high enough it worries me. I would never choose to rev a cold motor like that. Warm it up, tap the pedal and it just purrs. It's about 25 degrees out there this morning and I'm almost worried about starting it. I assume this is a simple adjustment.