valve cover vacuum leaks

["checksix3" <jetjock11@xxxx>]

>>Beg to differ. Had terrible vacuum leak where passenger valve cover
overlapped timing chain cover (mating surfaces not quite flush).
Steady pin point stream of solvent would kill engine. If that isn't a
vacuum leak don't know what is.<<

Now wait, we need to distinguish between what's noraml and what not.
In normal operation there should be no vacuum under the valve covers.
I'm not saying you can't get some there if something's amiss, but if 
you're sealing the covers your covering up another problem.

>>Still have bad leak around timing cover crank seal. Most likely way
that air is entering engine is via valve covers (vs block seal).<<

The timing cover crank seal is a pressure seal, not a vacuum seal.
Try this: With engine running pull off the hose at your air cleaner 
from your oil filler breather. That goes into the valve cover right? 
Any vacuum there? Now cover the end of the hose with your finger and 
wait. Tell us what happens. I'm serious, try it. If there is a vacuum 
nothing will happen right? You'd only be plugging a leak wouldn't 
you? Come to think of it, why would a path to the induction system be 
ported into the air cleaner in the first place? Please, tell us what 
happens when you plug this "vacuum" source.

>Rich A just plugged vacuum leaks in his cam access plates, again 
under valve covers.<

Uh, is that the guy in MD? No comment...

>Have you ever heard of anyone running PRV with valve covers removed?<

Why yes, I have...no problem. Does your engine stumble at idle when 
you remove your oil filler? If that's a path into the induction 
system, that would be a pretty big leak right? Or put a rubber glove 
over the oil filler port, what does it do? Again, there is opinion 
and there is data. Port a vac gage into your valve cover and measure 
it...or maybe the guy whose the expert on idle speed control can 
expalin it to us. ;)