Oil Leak

[4x4HEMIrig]

  My 72 had a mild oil leak when I got it. During a spring shake down drive, I noticed the leak was significantly worse. I pulled the valve covers off, since I knew that's where the leak was coming from. I realized the last owner had put 2 cork gaskets under the Edelbrock covers and that the covers were bent. I ordered a new set of covers, gaskets and hold downs from Summit. I ran into a problem with the PCV valve. Both the new covers are keyed for oil filler caps. I headed over to my local O'Riley's and found a sealed breather cap with a grommeted hole in the top to insert the PCV. Here's a before pic and some pics of the completed assembly. 

Enjoy.

-Aaron

[MEK-Dangerfield]

Aaron,

  Since you have a PCV valve in place, you should have a breather on the other valve cover. You won't believe this, but I can help you here.     On the opposite side of the Mopar script from the oil filler cap is a punch out. See that silver dollar looking thing? That punches out so you can add an air breather element.

[4x4HEMIrig]

The old covers didn't have one and the guys at O'Rileys didn't say I need one with the PCV. How would having a breather change the operation of the motor?

[Bullitt-]

Breather provides a  Vent for the PCV to suck air through

[72rtchallenger]

Breather provides a  Vent for the PCV to suck air through

yes needs a breather

[4x4HEMIrig]

Sounds good guys. I'll make it happen.

[dodge freak 2]

The old covers didn't have one and the guys at O'Rileys didn't say I need one with the PCV. How would having a breather change the operation of the motor?

i
Guys at O'Rileys are right--no need for a breather-just let the vacuum build up in the motor until a gasket leaks, lol

The breather provides fresh air for the pcv vacuum. The pcv sucks the fumes out but those fumes need to be replaced with fresh air.

 

[4x4HEMIrig]

Okay.

Q1. Does the Breather need to be on the same cover as the PCV, or can I replace the oil filler cap on the other cover?

Q2. Even though the PCV leads into the base of the carb, I still need a breather?

Question 2 is why the guy at O'Riley's said I didn't need the breather. He's got a Chevelle he built about 10 years ago, I figure he knows a hell of a lot more than the chick who couldn't even find a part when I gave her the exact name of what I was after.

-Aaron

[72cudamaan]

The breather needs to be on the opposite side of the pvc, otherwise you would just suck fresh air across the inside of the valve cover. AS to Q2, thats exactly why you need a breather.  You are sucking fumes from the crankcase, so you need a form of replacing the sucked out air (ie breather )

And there is a good reason people work at O Riley's. They cant get a job at a real auto parts store.

[FJ5_440]

A1.  The other valve cover is a good place to put the breather.
A2.  The vucuum from the base of the carb will depressurize the crankcase, but the air it is drawing in needs to be replaced to equalize the pressure.  The breather will draw in clean air to replace the stuff being sucked out through the PCV.

Early small block Chevys had a crankcase evacuation system which did not vent through the valve covers.  There are lots of guys who run breathers and not PCV valves, but on a street car the PCV valve is a pretty good system.  The Chevelle guy might fall into one of those categories.  Or he might not know any better- he is a Chevy guy after all.

[4x4HEMIrig]

Cool, thanks guys!

I was going to make the Chevy comment, until I realized some of the other guys here own those too. 

[wally426ci]

You guys have me curious. How come stock small block valve covers don't have a breather? Just cap on one side and PCV on the other..? 

[Aussie Challenger]

Some of the filler caps act as breathers, also when you stir the motor up pressure will build up inside the motor and the PCV cannot handle all the extra so it then goes out the breather, that is why you can get oil deposits around the breather. If no breather then the pressure will blow out a gasket or seal, that is why race cars have catch cans instead of breathers.   

[Bullitt-]

You guys have me curious. How come stock small block valve covers don't have a breather? Just cap on one side and PCV on the other..? 

UHHHH Look again

[Aussie Challenger]

Clean looking engine bay Bullitt,