Have recently converted my 312 engine to a Ford Autolite 4100-1.08 carb & a PCV setup. Used a later style rear vent valley cover for the valve location. It's not a fully closed system & the air intake is thru the oil filler cap. (clean & in good shape)  We've got the carb sorted so the idle is good. At idle the PCV seems to be working fine, virtually O crankcase smoke at the fill pipe. However, after driving it briefly, it's now blowing oil smoke when accelerated. I pulled the valve out & looked into the original oil deflector underneath & found noticeable oil residue there  So, first question is, am I using an incorrect PCV valve ?  The one I have is new but I had it on hand & don't recall what it was for originally. The # on it is 2072, USA made. I read somewhere that the valves need to be sized properly for the engine ?  Is that correct?  Thanks.   


Paul

PCV valves are application specific.  Since there is no valve specific to this application, the best chance at getting one that will work is to choose one for a similarly sized and performing engine.

If the valley cover has the baffle, then there could be something else going on.  If it doesn't or it is compromised somehow, you can try a baffled grommet to see if that helps.


Lawrenceville, GA

Charlie; thanks.. Does anyone know if a baffled valve will will fit over top of the original oil deflector?. Or will say an early (?) Ford 289 valve work?  Some later PC Valves have a double oulet for a closed gas vapor system connection, which isn't what I need.  Any info appreciated..    


Paul

I just added a PCV System to my re-installed Engine. I used a Valve I think for a 302 Ford. I can tell already its too much Flow at Idle. The last Time I did this was 10 Years ago and ended up using One for a 78 Fairmont 4 Cylinder. Its usually a Case of experimentation. I used one of those Baffled Inserts because I am using Original Valley Pan and these Inserts are supposed to Work with a PCV. I did have to add a Grommet correct Size for the PCV Valve. Cut it down and Glued to the Baffle to hold the PCV in Place.

  

Mark: Thanks.. Not sure what you mean by too much flow at idle, in what way?.  Further, I did some searching on PC valves & as far as I can determine, the #2072 may be from  Delco & it was indicated that it was used on smaller engines,"max size" 3.8 L V-6 or 232 inches. If that's correct (?) the one I have is way off ??. Will a unit for bigger displacement, be less likely to suck up oil or make it worse?? I'm Confused?!  


Paul

The PCV Valve has a Spring inside as well as a "Stepped"  restrictor which controls Air Flow. The Spring works against Engine Vacuum to keep the Valve in a Position to allow only a certain amount of Air to pass to Carburetor. If too much Air passes through at Idle you will think You have a Vacuum Leak. Rough Idle. Too much Air is causing a Lean Fuel Mixture at Idle. All PCV 's are calibrated for a Specific Application so the Trick is to find One that works Like I mentioned the last One I used was for a 78 Ford 4 Cylinder. The 302 One allowed too much Air at Idle.

  

Sometime in the past, greenbird56 had a post about using a restriction in the PCV hose to control the airflow. I don’t have much luck using the search function but you might give that a try. IIRC, it went between the PCV valve and the carb.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

I could use that Info too if Anyone finds that Post and can U put a Link on this Post? Thanks

  

When the PCV valve was put in the rear hole in the valley cover, was the hollow threaded stud for the original road draft tube retained or cut down?  I typically remove that hollow stud when I install a grommet in the valley cover hole.  This allows the PCV valve to fully seat within the grommet and still clear the 'shelf' beneath the valve.  If the stud was removed, was what remains of the original threaded hole plugged?  I just put a 1/4-20 bolt and self locking nut in that hole in the lower shelf which prevents a direct path for the oil to get to the PCV valve.  It's also important to insure that the shelf has not been pulled higher or upwards towards the PCV valve as that could have happened when the original road draft tube was over-tightened thus pulling the shelf up higher.
  
I use the Microgard 2322 PCV valves for the Y engines.  These are used with the more modern carburetors that are also designed to use PCV valves.  Early carbs tend to be on the lean side when retrofitting PCV valves and will require some tailoring of the idle circuits to richen up the fuel mixture accordingly.

Lorena, Texas (South of Waco)

Ted: Thanks. I should have mentioned that I did remove the attachment pce from the oil shield & soldered a pce of metal into the hole. The shield appears to be flat & the valve I'm using is only 3/4" deep to the flange & seats fine. However, I was concerned about oil drainage, so I drilled 3 small about 1/16" diameter holes around that area. So, that was probably a mistake to do that?.  If it matters the carb is similar to the Autolites introduced in 1957 but is actually original to a SBF, 289 Mustang, of 1965. (paper with it indicated it was apparently redone by Pony Carbs, before I bought it & appeared unused )


Paul