[Sophisticated Redneck]

Now assemble the vacuum control valves. Drill and tap the valve with 1/8" NPT and install the 6AN to 1/8" adapter.

I cut the spring about and 1/8inch shorter to allow more adjustment. Turing the body in will increase spring pressure on the check valve and decrease crank case vacuum, loosening it will increase crank case vacuum.

If you run much more then -10 psi crankcase vacuum, air will start to be pulled past the main seals from the crank case vacuum and make a screeching noise similar to a slipping belt. If you hear this then screw in the vacuum control valve body to increase spring pressure on the check valve and decrease crank case vacuum.