What is this part that is screwed into the intake manifold, between the rear of the carb and the distributor, (the thing with the bit of yellow paint on it). It has a 3/8" hex cap on it that can be rotated about a half turn or so in either direction before it stops.

What is it, what does it do, and how is it "set" if indeed it needs setting? I can't find any pics or mention of it anywhere in the repair manual.


1962 GT Hawk 4sp