What's this hole in my air filter housing?

[FishNinJay]

What is this opening? And what's it's purpose in my life?

Replaced my dirty air filter with this fancy Edelbrock 10" air filter and housing. There is this outlet (or inlet?) on the bottom, that isn't on my prior 9" air filter, or on a similar 9" specter air filter housing. I don't think it's for a breather, because it would be upside down, and probably wouldn't have room? Someone said it is for tubing from my PCV. Is that right? because my PCV tubing is going to the front of the carb already. Should I disconnect PCV from base of the carb, and move it to the air filter? Cap the carb port? or Cap this opening? Or just leave it open? You can see the filter gasket blocks some of the outer half of this opening.

If I do cap this? What can I use? I saw some vacuum caps, but largest was 3/8, which I think looked too small for this opening?

Ok.. as always.. much thanks!

 

[68LC]

It's to supply filtered air for the crankcase ventilation system. Vacuum is applied to the PCV valve, which evacuates fumes etc. from the crankcase. That fitting should connect to a valve cover, or other access to the crankcase. See attached link for the full theory behind a closed crankcase vent system. A link is worth a thousand words.

http://www.filtercouncil.org/techdata/tsbs/94-2R1.pdf

Right now that un-used fitting is just allowing unfiltered air a direct conduit to the engine internals.

 

[FishNinJay]

hmm.. very informative. Now I'm thinking I should change my PCV valve also, while I'm freshening up things on my new rig. So, I'm still a bit confused as to exactly where I should connect this opening to my manifold? and then change out my oil fill cap? Sounds like for now, I can just cap this, and continue to use my oil fill cap as an open PCV system? Again, thanks for the useful document!

 

[FishNinJay]

hmm.. just found this on Google Images..

So.. I need to buy a sealed oil filler cap with a hose fitting?

 

[D'Animal]

On most later built cruisers, you have a vent that contains the PCV valve and a hose connected to where yours is. You also have a vent coming from the valve cover to the air filter. You open hole should go to the valve cover hole. If you do not have a vent in your valve cover, cap the hole in your air filter.