Hi.  I have a small threaded hole to the rear of my valley cover near one of the two cover mounting bolts.  Mine is off at the moment for a gasket change and freshen up.  The hold is recessed and is seen at the bottom right of this pic.  Some sort of breather perhaps?  Can someone tell me what this is used for?

That hole with the threaded insert at its middle is for a road draft tube or a PCV valve vent location depending upon the year model.  Here’s a picture of a ‘60’s pickup engine with the PCV hookup still in place on the valley cover.

 

Lorena, Texas (South of Waco)

Thanks Ted.  Much appreciated.

If You ever want to do away with the Road Draft Tube and install PCV System You have the correct Valley Pan. They can be hard to find as opposed to the standard Valley Pan. 

  

Further, the photo Ted posted has the original "teapot" look connection that was used on original late Y-Block PCV setups, which had an inline (long) PCV valve fitted to it.  It's also possible to go a different route, by drilling out or removing the raised connection piece in the center of the hole & using a suitable PCV grommet for use with a short PCV valve, that will clear the splash guard underneath.  Not sure, but I think some people have used a SBF 289 or 302 valve?..   


Paul

Thanks for the info.  It hadn't twigged that it was a PCV.  It didn't have anything connected so I'll see what I can buy new.

Here’s a picture of the late model valley cover retrofitted with a grommet so it can accommodate a PCV valve.  As Paul mentions, the center threaded post was removed to make room for the PCV valve.
 

Lorena, Texas (South of Waco)

Hi Ted.  That pic is very helpful.  What PCV and grommet did you use?  I realise I need to drill out the old tube.  Was the grommet anything special?  Cheers, Lloyd

The grommet is a Dorman #42323 while the PCV valve is a Microgard PCV2322.  Both of these items were obtained at the local O’Reilly’s parts store.

Lorena, Texas (South of Waco)

If You install a PCV System You may have to experiment with PCV Valves. For some Reason a PCV Valve Someone has used on One Engine does not work on another. Sometimes too much Vacuum at Idle. I used One from an early 80's 4 Cylinder Fairmont. The One for a 289 allowed too much Vacuum.