On a Chevrolet truck with a V8...One valve cover has a PVC valve and the other a push-in breather. Would it hurt to put a second PVC valve in so I have one on each side and run 3/8 hose to a T fitting then to the carburator? Good/Bad/Wouldn't hurt?
I own a shop, and understand the system. You must have a filter on one side that allows air to flow into the crankcase, while a metered (PVC) amount is pulled through the engine for a complete evacuation of the crankcase. If you tie both ends together, you would have no air flow through the engine. What it would do is; build up pressure inside the engine, and force the oil out every seal, and crack in the engine. In othe words, it would use oil in a bad kind of way. Air must enter the engine, travel through the engine, and go back through the combustion side of the engine, and exit out the exhaust system. The vacuum inside the crankcase is a different system than the combustion side. If an engine does not create the correct amount of vacuum inside the crankcase, the piston rings will not seal as they should, and allow combustion to enter the crankcase building pressure. The PVC valve is a metering check ball that allows air to flow one way, but not the other, thus hooking a hose between the two sides will not allow the engine to ingest fresh air from any where. The vent cap for one side is a filter, and allows the fresh air to enter the engines crankcase. The air travels through the engine and evacuates the blow by gases from the piston rings. Equal amounts of pressure on both sides of the rings is what keeps the gases from just blowing past the rings. A pressure is actually built up between the top, and the bottom rings that make the rings expand and seal off even better. Upset this pressure on either side of the rings, and you have an engine that uses oil. It will either burn the oil, and/or throw the oil out of the engine. Its not really complicated how the system works, but disrupt the flow, or not have an equal amount of pressure on both sides of the piston rings, and you will have an unhappy engine. This applies to stock engines that come from the factory with a PVC system. Glad to help out, Good Luck!!!
Leave the breather in, you need the freshair to enter the crankcase. Esentially think of the breather a the entrance for the air then it goes through the crankcase and up the other valve cover back into the intake/carb with all the oil vapors. If you wanted to run a closed system could put a line from the valve cover with the breather to the air cleaner.
No No No, The PVC valve removes a measured amount of crankcase blow by, oil vapor and water to be re-burned in the combustion chambers for emissions standards. The breather in the valve cover is needed to let atmospheric pressure in the crankcase to replace the air the PVC valve and hose has already been removed. I think you've been reading up on dry sump systems. Race engines make more power with a crankcase under vacuum while running.
