how to adjust vacuum advance
With the vacuum connected you should have about 50* at about 3000rpm.
Vacuum advance only works when there is high manifold vacuum, rpm has nothing to do with it. The only time you will see 50 degrees is when you are cruising with the rpm above the point that full mechanical is in, the throttle is mostly closed and there is high manifold vacuum.
gotdust57, if your 360 is mostly stock you should not need to do much to your distributor. The distributor will have around 24 degrees of mechanical advance built into it. So you initial timing at idle (vacuum advance disconnected) of 10-12 degrees BTDC will give you the 34-36 degrees of mechanical timing the motor will want to see. If you have a dial back timing light you can confirm this by setting the intial then reving the engine until the timing stops advancing and use the dial on the light to bring the mark on the damper back to the zero mark on the timing marks.
You will likely find that it takes well in excess of 3000 rpm to get the timing all in. This is where you can make a noticable difference by changing the springs and having it all come in in the 2000-2500 rpm range. If you pick up the Mopar Performance spring kit that has two springs in it replace the heavier of the two stock springs with one from the kit. Note: using both will have it all in at to low and rpm for a street driven vehicle.
The arm on the vacuum advance module will have a number stamped on it, something like 7, 8, 8.5, etc., double this number to get the number of degrees of advance the vacuum advance can add. Add this number to the total mechanical advance to get the 50ish number previously mentioned. Remember the vacuum advance has no impact on performance, its there to improve cruising efficiency and mileage. The engine will very seldom see all 50 degrees of timing.
To adjust the vacuum advance without a ton of trial an error you will need a vacuum gauge and a vacuum pump with a gauge. Hook up the vacuum gauge to a manifold source and drive the car with the gauge mounted so you can see it. Find whet the manifold vacuum is when cruising at a steady state speed on level ground. Now use the vacuum pump to see what vacuum is required to get full stroke of the vacuum pot. Now you use the allen wrench to adjust the pot so the full stroke is obtained at your steady state cruisng vacuum. Now drive the car if you have no part throttle detonation your ar done. If you do you will need to back off on the vacuum pot adjustment until you don't.