Dual Point Distributor Vacuum Advance Spring

[toolmanmike]

This should help you can see when the screw is all the way out CCW, it compresses the spring I the vac advance, usually takes over 20 INHG to move the diaphragm when it is out all the way. when in CW they usually start moving at around 5 INHG, hope it helps explain it.
View attachment 77051View attachment 77052

View attachment 77053

Screw out, less spring tension, less vacuum to operate it.
Screw in, more spring tension, more vacuum to operate.
I don't know how long the screw is but if it is screwed in far enough it could disable the diaphragm.

 

[halifaxhop]

.5" tops