Hot Rods Motor Minder Gauge

Just got one of the Stewart Warner Motor Minder vacuum gauges and just was wondering if anyone knew what the screw adjustment on the back is?

When you take off the fitting that connects to the vacuum line there is a small adjustment.

 

Probably an adjustment screw the factory uses to "0" the gauge during manufacturing. Don't mess with it if the needle is on zero with no vacuum hose attached.

 

When I did have it Hooked up I pulled the line off the front of my carberator. Quadrajet.

At idle is was about 13 to 14. Which seemed low since I thought it was going to be around 20 at idle. Could it be just a stickey valve?

 

Alright thank you. I didn't adjust it, just wanted to see what it was

 

I believe it is the "trim" adjustment to smooth out the needle movement. As above, don't mess with it.