Does anyone know if the Holley #120-140 TB Air Foil Blocks or interferes with the PCV passage in the TB ? I am considering purchasing one, but do not want anything to affect the PCV system functioning correctly.

This is on stock 1995 LT1 throttle body.

 

If it blocked anything it would seem be the idle air control passage. I can't tell from the hi-Res photo on the Holley website whether it has the required hole(s) in the face to allow air to reach the IAC passage and the small blade bypass hole.

These things are only worth about 2 HP, dyno proven. Check the mods dyno tests on ws6.com

 

Thanks Fred, I appreciate the input.

 

When you look between the throttle bores, the 1/8" hole at the bottom of the TB supplies idle air directly to the intake manifold. Below that hole, behind the bump on the floor, there is a hole that feeds air to the idle air control valve.

There is another "bump" on the top of the upper triangle, and that is intended to supply air to the passenger side valve cover, and that is the air that the PCV valve pulls through the crankcase. If the PCV isn't working, or there is excessive blowby in the crankcase, the crankcase vapor will blow out of the valve cover, through the chamber under the top cover of the TB, and into othe intake manifold, often accompanied by entrained oil mist that was picked up in the valve cover.

There has to be air flow to all of these locations.



This is an airfoil that dates back to the mid 90's, and it worked fine on my LT1 - note the holes at the bottom:

 

Thanks Fred, that is exactly the information I was hoping for. This is great, thank you !