Valve Covers - help pls

I just got a 69 Camaro with a 307 engine. Im very new to these cars and engines, but Im looking to learn. One of my valve covers has 1 hole on top and the second valve cover has 2 holes. The cover with 2 holes has an oil cap covering one of the holes and nonthing covering the other hole. After I drive the car for a while some of oil is on the underside of the hood right over the uncovered hole. Any idea whats supposed to be connected to the open hole? I tried to include a picture so you can see what I mean.

Also, Im going to replace the valve covers with a chrome ones. Should I just buy a valve cover with only 1 hole?

Hope someone can help.
Thanks.
Bill

Hi Bill and welcome to AF.

The open holes in each valve cover are for the PCV (positive crankcase ventilation) system, or, some folks just run filtered "breathers". The one with the cap is for adding oil to the motor.

The PCV system is the best for the environment (emissions) and less fumes into the cockpit.

Leaving these holes open, as they are, introduces dirt particles into the engine and is not a good thing.

Do an internet search for PCV systems to see how they are hooked up and work.

Also, after market valve covers just come with one breather hole in each.

Thanks for the advice. I researched it on the net....learned a bit more about PCVs. If I went out and bought an after market valve cover (with only one hole - for the oil) and replaced the existing one, do you think Id be all set and therefore wouldnt have to fool with the PCV?

Bill

On valve covers with 3 holes for both as mentioned, 1 for oil fill, 1 for pcv, 1 for breather going either to air cleaner housing or stack under air cleaner.
PCV valve system would be advantageous to your engine and the passengers. The engine through its combustion process builds gases which need to be evacuated for performance as well as a host of other processes. Oil leaks and carbon build up are 2 of the problems associated with lack of engine breathers.
Prior to PCV, Older engine designs used a draft tube similar to the diesel engine to remove these gases.
I suggest using the PCV system and either a breather or a vented oil cap for the best results.

Good post, above.

If you do go with valve covers with only ONE hole per cover....... one hole is used for the PCV and the other hole is for a breather or vent pipe........ and no filler cap. You would remove the breather or vent pipe from the valve cover to add oil.

Also, the hole for the PCV valve should have a simple metal deflector below it. This prevents oil from splashing directly on to the PCV valve itself.

BTW..... do NOT do what my buddy did on his Chevy 350 V8. He used a PCV valve only, and plugged the other two holes with rubber oil filler caps........ no vents at all. Since the PCV valve is too small to vent crankcase pressure under heavy throttle, he blew out all his crank oil seals. :(