Non-Linear Vacuum Regulator Valve

There are 2 input ports on the NLVR: intake manifold vacuum and carburetor ported vacuum. One outlet port connects to the distributor vacuum unit. At curb idle, regulated vacuum is supplied to the advance unit. When manifold vacuum is high and ported vacuum is very low, the NLVR regulates the vacuum signal so it is between these two vacuum source levels at idle. As engine load increases and ported vacuum signal is above 7.5 in. Hg, regulator valve switch to ported vacuum output.