1952 8N blowing oil out of filler tube.

Ford specs: 90 psi min. Crank for 5 puffs and rite it down. Now put a spoon of oil in same cylinder. 5 more puffs and wrightitt down. If compression only increased about 10-15 psi. THAT cylinder is probably good. If increased 20-30 psi, you may have stuck rings or worn rings, eather of which can contribute to filler tube "blow-by". Stuck rings can sometimes be un-stuck with Marvel Mystery Oil. If no increase, may have a burned exhaust valve.

And if you don't believe me, ask your local automotive mechanic..... ....Dell

Damn, I'd forgotten that important advice -- my compression
had already tested good when I was having that problem.

I searched the archives and found lots of advice,
like:

be sure the baffles inside the tube haven't been
bent out of the way

be sure the air slot in the bottom of the filler
cap is not obstructed

be sure the filter element is clean

and many others, but the one that worked for me
(mentioned only once in the searches I did) was:

be sure the filler cap is oriented the correct
way! (the slot on the side should be "uphill"
(toward the engine), as should the tiny hole
in the bottom plate. Some oil gets forced up
into the cap, but if you have the slot and hole
uphill, it doesn't drip out. Works for me (so far).

Good luck. Do a search if the above don't apply
to you, because there were lots of other
suggestions including rebuilding your entire
engine ;).