My valve covers are identical...............2 oil caps and 2 holes that pcv valves fit into, I have now 1 pcv valve and the other hole empty, so the question is should I put in a T fitting and have one on each side or does it really matter? Thanks for responces

One PCV is all you should run. A lot of the valve covers have available holes for different configurations.

you need the 2nd hole for "venting" the crankcase, with an oil type filter/breather,or you could run two P.V.C. but it will make some noise when you shut down the engine.(air passing by the seals make a squeel) I think its best to "vent" the crankcase..:poke::dontknow:

If you knew the internal design of a smallblock, then you would understand why only one is necessary. As long as the backpressure is vented (either side) your good to go. You should be able to find a rubber grommet to plug the unused side at a good parts store or speed shop, all you need to tell them is what you need and what size diameter hole you need to plug...but talk to a knowledgeable sales person...not the person working there just to have a paycheck...they won't have a clue what your talking about.

so the other hole will or will not be sucking air to some degree???

ok ,just so I understand, a gromet is a rubber part with a hole in the center, is this what I want or do I need to PLUG the hole with a solid ( no airflow) gromet?

Are the oil caps solid or vented? If they are solid you will need a breather on the side opposite the pcv.

Best to have either a breather cap or a line to the Air filter for clean air on one side. The PCV "Sucks" fumes from the crankcase, and requires "fresh air" from the other side of the engine to provide flow of air. If you have two PCV's, then you are sucking on both sides of the engine, and creating even more vacumn in the crankcase. If you plug one side, you will still create a vacumn in the crankcase via the working PCV valve in the other valve cover.

By the way, you want to suck those fumes out. If left in the crankcase, water vapor will condense, and mix with the fumes, creating an acid mixture that can eat away at the internals. If plugged, you can build pressure in the crankcase that can blow out your valve cover gaskets, etc.

So bottom line, one PCV valve on one side, one breather cap on the other.

got solid caps so a breather it is..........glad I asked............thanks guys