Back when I removed the road draft tube I just removed the long screw and popped it off leaving the screw shaft in the valley pan. Then installed the grommet and inserted the PCV valve. If the PCV valve is fully seated up to the collar the screw shaft in the valley pan will insert itself into the PCV valve preventing it from closing. I taped a piece of aluminum foil to the base of the valve and inserted it approximately 4/5 of the way into the grommet. When I removed it I could see a clean impression of the valve base with an indentation where the screw shaft had pressed the foil against the valve base. I then replaced the valve leaving an approximately 3/8 inch reveal before the collar, that should leave enough room for it to close.
My understanding is the valve is to be open only under high vacuum conditions ie when idling. My question is with the valve always open can the additional air be causing a lean fuel mixture condition?



1955 312 T-Bird Warwick, NY

What I was told many years ago is the particular valve is set up to meter the airflow at full manifold vacuum. The closed position happens from a backfire, to prevent igniting the vapors in the crankcase and blowing out the gaskets. I have no reason to know whether it’s true or not. That said, your solution might work. If not, the right valve in-line in the hose (elbow if needed at the valley pan) might be the other solution without pulling the valley pan.

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

It’s best that the PCV valve does not have that tube protruding into it if for no other reason than to prevent the oil from having a direct path into the valve by way of that hollow tube.

One option is to bend or pry that hollow threaded stud over to the side to get it away from the PCV valve.  Another solution might be to use a ½” deep socket placed over that stud and drive the inner plate down.  3/8” might be enough to accomplish what you need and potentially more if the cover is actually bent upwards which is sometimes the case when the road draft tubes are overtightened.  My own preference is to just remove that hollow stud with the valley cover off of the engine and then put a smaller bolt in the remaining hole to prevent any oil from having a direct path to the valve.

Lorena, Texas (South of Waco)

Great advice Ted as always, many thanks.

1955 312 T-Bird Warwick, NY