Hey guys, Should the valve cover breather hose have pressure or vaccuum? I have vaccuum on mine ( 72' 240 ) I was under the empression that it would have a small amount of pressure out. The hose that connects the block to the pcv on the balance tube sucks vapor from the crankcase -- is this where the vaccuum in the valve cover is from??:cross-eye

I have seen discussions about the breather on other lists. The valve cover breather should be attached to the air cleaner and is under vacuum. I have heard arguments that this helps draw gas vapor and other contaminant gases from the valve/cam area as well as equalizes pressures.

But that is just what I have heard, any experts out there?

Have fun!

Royce - Thanks for the reply - Wouldn't the valve cover have some vaccuum on it because of the pcv port attached to the carb. balance tube??

The valve cover breather is attached directly to the air cleaner and yes would be under vacuum. The PCV draws vapor out of the block by vacuum.

But I don't know if a bad PCV valve allows more or less vacuum or maybe to regulate pressure at various RPM levels!?