TR6 ZS 175 What does this screw do?

[Chirs C]

I have a '76 TR6 with ZS 175CDESVX. Can anyone explain what this screw does? It actuates a plunge when the throttle is opened and also has a smallish effect on the idle speed. The books I have don't seem to mention this adjustment.

 

[poolboy]

Normally there's a locknut around the screw you're asking about.
Read the text next to the 5th picture on this page:
https://www.buckeyetriumphs.org/technical/Carbs/CarbsII/CarbsII.htm

 

[Chirs C]

Thanx,