Rear crank seal is one of the most common leak points from an engine that passes its first few thousand miles without leaks. Once you get an engine sealed up, it should stay that way for quite a while. Excessive wear and (if you run a closed or insufficiently vented crankcase) crankcase pressure will eventually create leaks, often starting with the rear seal.

There's a lot of opposition to PCV just because it's "smog equipment" - but in all truth, every engine should have some form of crankcase venting, ideally assisted a little by a vacuum pull to force the venting under all conditions. Reducing crankcase pressure saves seals and gaskets, and getting the hot vapor out of the case (and ideally burning it in the cylinders rather than just venting it) prolongs oil life.

Okay, slight change of direction but I'll just extend this thread.

I have two or three solutions to gate the rear breather hole to manifold vacuum. One is to use the kit that Gessford put together, which puts the PCV valve in a Dove plate in the breather hole. Tube to carb vacuum, done. It's okay but not terribly good-looking, and it's $90 besides.

The other option is to use an OEM breather plate with a tube nipple on it, which I think was used with an inline PCV valve (tube in, tube out to carb). Not bad but a little... OEM-looking for my taste.

What I'd REALLY like to do is use a thread-in PCV valve into one of the intake ports (there are two 3/8 NPT ports I'm not using) and just run a tube to the OEM plate. The problem is that most PCV valves I've found with a threaded end have the vacuum connection on the other, tube end. I need to find a PCV valve that has a 3/8 NPT threaded VACUUM end, with a tube (or any other kind of connection) to the actual crankcase port.

There are ten zillion PCV valve styles; there must be one like this in the parts books. Does anyone have a clue how I'd find the part number from, say, NAPA? Anyone know of a parts source with purty pitchers of all the different valves, or something similar? I've browsed the local parts stores but found nothing hanging on their hooks.

Napa has pretty pics
 

GO to this link NAPA's on-line catalog, I just searched pcv valves.

http://www.napaonline.com/NOLPPSE/(S...Dn=0&Dk=1&Dp=3

Aces. Exactly what I was looking for - I knew someone had a full pictures site for this, just couldn't find it. Of course :JEKYLHYDE it's NAPA.

Shortly after having this NAPA catalog to browse, I found a PCV kit for FE's on Ebay. It's a nice kit - aimed at the tri-power crowd, but adaptable to any FE with a rear breather port.

Nice, but $150! Even Gessford's nice one is only $98 and includes an aluminum Dove plate. The Ebay one uses a repro of the black steel Ford plate and nothing else fancy at all. I'd guess it at about $60 in parts, including the expensive filter basket. $150 is such a gouge. Its only advantage is that it does use a PCV valve that screws into the carb or intake.

From the picture, I could match it to the NAPA catalog. I've now found the PCV valve with a screw-in vacuum end. Six whole bucks.