<VV> Fwd: PVC Valves Explained?

[Matt Nall]

 <jaysplace at laserpubs.com>






A standard PCV valve has a spring-loaded restrictor, to limit flow at 
high manifold vacuum and allow greater flow at low manifold 
vacuum/higher engine load.

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 Jay!!  How did you figure this out???  gggg


A PC Valve is a ONE WAY CHECK VALVE......  if the are clean.. they rattle????


 The ONE WAY  is to prevent Crankcase Explosions caused by carb Backfires!!!


Early units had a just an orifice....with a plunger to clean!!... but many pan gaskets and valve cover / valley cover gaskets were lost!! ggg


  Yes there is a difference in orifice size  depending on the engine..and the amount of blowby  expected under normal conditions...but you can enlarge the orifice,  lower the throttle opening and richen the idle Mixture to compensate.


  Sadly , a Fixed orifice  allows only so much flow... and with vacuum being highest at idle.. it only gets worse as vacuum falls off...  High Throttle openings....


Someone talked about a VENT  being needed to be a "True  PCV  system"......  BS!  A VENT  is what lets Moisture into the crankcase...but we need one for when blowby volume is higher than what the PC valve can flow...


  Exhaust powered systems, normally used by drag racers,   can pull enough volume  to cause a negative pressure... there by causing better ring seal..and use no vents!


Kevin Willson's setup


http://corvaircenter.com/phorum/file.php?1,file=27129,filename=HEADERS.JPG


http://corvaircenter.com/phorum/file.php?1,file=27131,filename=blowby.jpg





Matt Nall
Charleston, Oregon
http://tinyurl.com/The-Corvair-Patio

http://tinyurl.com/Matts-Tech-Pages