Hi,
I'll bite.
You can pressure in your crankcase for a number of reasons. There's the
obvious blow-by from bad rings which is more a less a "worst case"
scenario. However, I'll presume that your motor is recently rebuilt or in
relatively good condition.
Guess what, unless you have "total seal" rings, you still get quite a lot
of blow-by, especially when you decelerate by taking your foot off the
accelerator pedal.
So, you either need to set up a PVC breather (as you mentioned) or you
can do the following racer trick: get a "catch can" and plumb it to the
vent line on your valve cover. Then when the case pressurizes, the air
should vent to the catch can.
The right way to do this is to use a can with a breather filter on it,
although a lot of folks just have a hose the terminates in a can that is
securely attached to the firewall (or other body part). I think the rules
say: you need a catch can and it has to be secure. There's a lot of
interpretation available, because the installations that I have seen are
pretty well varied.
Places like Summit and Pegasus sell real fancy aluminium catch cans with
AN fittings etc. They look great and are costly too!
Personal note: when I put on my Webers, I was getting oil all over my
engine compartment - especially at autocrosses. It took me a while to
realize that I was seeing blow-by, and the Weber manifold (Cannon,
actually) had a tap in it for a hose, but it only had a small fitting for
the vacuum retard/advance... I drilled it out and welded on a barbed hose
fitting for 1/2" I.D. heater hose and ran that line to the valve cover.
NO MORE OIL IN THE ENGINE COMPARMENT!!!
C ya.
rml
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