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.

[Dead Parrot]

Should be a fast idle adjust screw somewhere in or near the choke linkage. It most likely will look similar to the normal idle speed adjust screw. Location depends on the carb.

[76shuvlinoff]

Originally Posted by Dead Parrot

Should be a fast idle adjust screw somewhere in or near the choke linkage. It most likely will look similar to the normal idle speed adjust screw. Location depends on the carb.

I looked for a fast idle screw and didn't see one. Doesn't mean there's not one there somewhere. I will get a mirror and check out the backside where all that linkage is. I tried to play with the auto choke adjustment and went too far, now it won't run cold at all. I sprayed WD 40 around looking for an intake leak. Found nothing. The carb is a Rochester Monojet, original equipment.

Thanks

[rpmerf]

Note sure that is the same as your carb. You can see the fast idle screw in this image. it should be in a similar location on most carbs. On the throttle shaft, connected to the choke.