Heavy Breathing (No, not that)

[David Doddek]

>Fellow DIY's,
>
>This question has been going around my brain for a few weeks now.  My TPI
>350 (when I'm racing) seems to breathe oil vapour, quite heavily, out the
>rocker covers, at idle and normal drive its fine.  The rocker covers are
>naturally aspirated (ie, just vented to the open via a breather cap in each
>cover). No PCV or other hose work to the intake system.
>
>Now, the motor has quite a high compression which I'm contributing to be the
>main problem.  Oil pressure is also very good ~70PSI at 3500-5500rpm.  I
>think that possibly the rocker covers are filling up, causing all the oil
>returns to the sump to be blocked, hence the crank case has to breathe
>through a few liters of oil.  Is there a way to fix this breathing problem ?
>I thought of venting the crank case to the open (ie. not through the oil
>returns and push rod holes, but a direct vent to the open), is this a good
>idea, or would it create crank case vacuum problems ?  If OK, can I use the
>spot that the mechanical fuel pump is meant to bolt on to ? Should I use a
>PCV so the crank case can only breathe out and not in ? 
>
>By the way, none of the seals or gaskets are leaking oil.
>
>Dan     dzorde at geocities.com
>
>
>

Sounds like good old fashioned GM Blow By to me.  Not much you can do about
it.  Change compression rings possibly.  Use a good oil vapor seperator on
the valve cover breathers and a PCV valve to suck the vapors down the engine
to keep the mess off of the outside of the engine.

David Doddek     pantera at pobox.com    www.pobox.com/~pantera    217-422-3722
69 EFI Fairlane, 89 T-bird SC, 74 Twin turbo NOS EFI Pantera #6825
If you are going to go fast, go real fast.