Well every intake will suck a little oil into the TB, you don't see it as much on a stocker because of where the PCV hook up is. I know on my Holley it is just a way of life, the trick is to run the PCV line to the airbox and that will clear it up and the oil will neve reach to the air box, that came from my friend who owns his own Performance shop, this is what he is doing to all his customer who run Holley intakes. I was running a gas filter inline on the PCV to catch the oil so it wouldn't drip out the TB. I have all my screens and baffles in but on my car it is due to the design of the Holley intake and location of the vacuum tree which the PCV hooks to.
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Check Out My Site 91GT,Holley SysteMAX II Kit-Heads 2.02" x 1.60" port matched to a 1262,Anderson N-61,24#,76mm C&L,Full MAC exhaust 1-5/8" Long tubes,2-1/2" O.R H-Pipe,2 1/2" cat back, No A/C or PS or emissions, 12" K&N Filter,RNH PERFORMANCE Ram Air,Ron Davis Radiator,Full Suspension,S&W 8pt "X" brace,JAZ seats,3:73's,Welds..etc,4:30's and 31 splines coming very soon!