Help with 1920 Holley carb

[sketch]

What is the part I circled ? What does it do? It keeps slipping out I need help I can’t foe the life of me find what this is

 

[RustyRatRod]

Choke linkage. The Jesus clip is missing.

 

[RustyRatRod]

Here's what the clip looks like. Don't go jumpin all over this one because I don't know if it's the right size or not.

1964-66 Pontiac GTO LeMans Tempest Carburetor Linkage Clip 66-67 Choke Rod Clip | eBay

 

[townsend]

Most auto part stores stock or can order these clips. Just ask for dorman #41016. This is an assortment pack of choke rod clips.

 

[sketch]

thanks guys. so new at this. now for the bonus question; there is only one screw on this carb for the fuel/air mix, right? is it yellow?

 

[Mattax]

The screw in your last photo is for adjusting the fast idle speed.

Service manual will you help alot.
MyMopar - Mopar Forums & Information - Service Manuals
Originals are available used and reprints are sold by various companies. Bishko is one.

A lot of very good information is in Master Technician Service Conference - Chrysler's Training for Mechanics
1966 222 and 1970 273 are two on how carburetors work.

Others get into specific mechanical adjsutments.
If some of the info is complicated then come back to it.

The 1969 master techs are also in The 1970 Hamtramck Registry Library Page (1965 - 1969)
which has lots of factory and dealer info. Some of which you and your son may also find interesting.