The test with a piece of paper over the hole of the breather shows it very clear if there is a suction or "pressure" from blow-by.
To test if you have any leaks to atmosphere or vacuum leaks on the valley pan gasket, you could do the following test:
-Disconnect and blank off the PCV hose tail with something. (also block the other side of the hose to the intake otherwise it will cause a massive vacuum leak)
-Remove the breather from the valve cover.
-Install the vacuum gauge and hose on the oil dipstick making sure it seals properly.
Now, when the engine is running at idle block the breather hole with your hand and observe the pressure on the gauge.
It should come up slowly,
do not exceed 3 PSI though.
By just releasing your hand the pressure relieves instantly and no worries.
If it builds up pressure it proves you don't have any excessive leaks from your crankcase out of the engine and/or a leak to the intake system through the valley pan gasket.
If there is no pressure build up it means the blow-by is able to escape the crankcase elsewhere, either to atmosphere or a leaking valley pan gasket to the intake.
If the pressure comes up really fast and high it means there is a lot of blow-by from the piston rings.
I recently tested this on my car where i had to keep my hand on the breather hole around 6-7 seconds i believe to reach 3 PSI.
A PCV valve actually several functions has 2 vacuum stages:
1) when there is a high vacuum scenario like at idle and cruising speeds the check valve in the PCV is pulled up fully against its seat inside the housing.
When it is in that position it causes a restriction in air flow, this is to prevent your engine pulling too much air at idle from the PCV and cause a lean mixture.
2) The other is the WOT mode, where the flow through the PCV is at maximum due to the low vacuum.
In this stage the check valve is in a floating condition and allows maximum air flow through the valve.
This is to get rid of all the blow-by in the engine crankcase during that high power demand as the cylinder pressure is high.
3) Another function is that it acts as a check valve in case of a back fire in the intake.
So, when checking vacuum build up at idle you are searching for it at the time of the least amount of vacuum being pulled from the crankcase.
The pcv is attached to a port on my intake.
I am not sure but i believe you hooked up the PCV hose to the intake itself?
I would recommend to install it on a manifold vacuum port on the carb itself, this spreads out the oil mist/fumes/low oxygen content gasses over all cylinders while it is mixed with the fresh air/fuel charge.
Now 1 or 2 cylinders (depends on what intake you have) need to deal with that crap and will run a different A/F ratio then the others. Plus the spark plugs will likely be oily compared to the rest.
If the blow-by equals or exceeds the vacuum at the PCV valve, you won't.
This is also a fact that you need to consider, but with the above test you can find out if there is a lot of blow-by.
Edit: You may consider cleaning the PCV valve with blasting a shot of carb cleaner and compressed air after it to get rid of any sludge/deposits inside, but blow from the valve cover connection to the hose tail end...the other way it will just close and blow the carb cleaner in your face/eyes.
Or just try another PCV valve.
