Air valve piston

[Smoking Nun]

Ok

for a 68 Classic, Actually Minimag valve

on the brass piston, on the back, is a big set screw.

How far, precisely, should the set screw be screwed into the back of the piston? I assume it makes a difference, since it would affect operating pressure?

Thanks,

Nun

[Smoking Nun]

some tech's gotta know this

Come on ya'll

Some tech's gotta know this stuff.

Nun

[BlackVCG]

Don't touch the black set screw in the back of the piston. It's preset to vent at a certain pressure. If you want to adjust the velocity/operating pressure of the valve, you tighten/loosen the silver nut on the back of the valve.