Heavy Breathing (No, not that)

[Shannen Durphey]

Coupla questions:

How much oil are we talking here?  Are you dumping quarts out the valve covers?
What kind of racing?  Straight ahead or left hand turns only?
What kind of vehicle?
What kind of compression?
solid lifters or hydraulic?

quick reply is that you're getting blowby past your rings
some circle track racers plug the LH valve cover vent hole, and duct the RH vent
to a homemade venturi in the exhaust.  I've seen a coulpe of drag racers duct
both valve covers to the exhaust.

dzorde wrote:

> 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