Valve Cover venting
Thread Starter
Pro
Joined: Dec 1999
Posts: 673
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From: Venetia,Pa,USA
Valve Cover venting
I'm installing different valve covers on a ZZ4 crate motor[ new cam,SuperRam]. They came with rubber inserts for vents. They need drilled. Is it necessary to vent both covers since the heads have oil return holes to the crankcase. If both sides need vented; WHY?? Is there too much pressure build up with only one side vented?? I have a recovery catch can. The car is a track car only.
Team Owner
Joined: Jan 2003
Posts: 20,305
Likes: 241
From: Summerland B.C. Canada
One valve cover takes in fresh metered air from TB. The other has the PVC valve hooked up to manifold vacuum. I see some just using a breather cap but i wonder what happens to afr when using unmetered air. 
