1967 Chevrolet Chevelle • 80,000 miles

Hi, I'd like to remove the PCV valves and just run a small air/breather filter in each of the two valve covers. Will this cause any problems with how the engine runs or it's performance? My car is a 67 Chevelle SS 396 that runs about 400 HP. I want to replace the valve covers with some nice aftermarket covers and when I do this I would remove the PCV valves if it won't cause any problems. Please let me know if it's ok to do this. Thanks, Rory

March 28, 2013.

What you should have is a PCV on one valve cover connected to the carb with a 3/8th vacuum line. The other side should be a breather type oil cap. If you just use breather filters it will vent through the breathers and make a mess on the top of the engine and valve covers no engine damage will happen just very messy.

Mar 28, 2013.
I disagree with racefan966. Eventually running without a pcv valve will cause oil and most importantly gas fumes to buildup within the crankcase because that is the job of a pcv valve, to remove and burn excess gas/oil fumes. Without a pcv valve, gas fumes will build up, which could one day not only dilute the engine oil causing lubrication problems, early bearing failure, etc. It could also cause the excessive crankcase pressure to blow out gaskets and may even one day lead to an explosion. Just suppose the engine would backfire for some other reason, with all them gasoline vapors floating around, it would make a bomb. The gasoline flowing through the engine oil may also lead to wiping the cylinder walls of oil causing premature ring failure, which would cause even more and more blowby and even more gas fumes building up.
So, to make a long story short, install a pcv in one valve cover and a breather cap on the other.