Fox Too much vacuum or what


New Member
May 22, 2022
92 5.0 gt40heads 351cam trick flow rollers Holley upper and lower intake bbk from filter to the mufflers new pcv and it's still sucking oil into intake enough that it runs out the throttle body and out the air filter and twice now it's blown a cloud of smoke on startup I'm sure if I stayed out of the pedal it wouldn't do that but I can't stay out of the gas pedal but I don't see that as being my solution
  • Sponsors (?)

The car is far from ratty or

clapped out


  • IMG_20220603_185732~2.jpg
    413.3 KB · Views: 44
  • IMG_20220603_185829.jpg
    793.6 KB · Views: 42
  • IMG_20220603_185732.jpg
    763 KB · Views: 45
Sounds like you need an oil catch can. Some intakes don't have a separator plate on the bottom of the lower intake. Without one it will suck oil instead of just oil vapors. The catch can goes in the hose between the intake and the pcv valve.
The Holley intake was all ways bad with sucking oil from the valley, used a later explore style baffle under the pcv on mine but it also has breathers on both valve covers on that car. It's mostly from the location of the vaccum source on the upper intake since Holley has it right at the throat it puddles oil there.
Last edited:
  • Like
Reactions: 1 user
All good answers
I would run a crank evac system on yours
The reversion they call it is what is putting the oil in your intake
Reversion happens during the time when both valves are open
Part of the scavenging effect
A few ways to control this
Crank evac, catch can, ribs in the floor of the plenum
Good luck
I get a kick out of Smoky Yunick's 302 Chev setup with the big steelies