Interesting
Are all the tube bottoms, where they go back into the head, oily? Wash and wipe them all and re run the engine to see where it is leaking.
The push rod tubes are aluminium and are 'swaged' into countersinks machined in the head top and bottom faces.
To
re-tighten in the top face (where the oil is probably dripping down
from) remove the rocker gear and push rods, ensure all is thoroughly clean
and using a conical ended piece of steel that is a bigger diameter than the tube. (about 1 " diam) Squarely tap it onto each tube with a
hammer. This effectively swages the tube outwards and re-makes the contact seal with the cylinder head.
I have had to do this on a TR head recently and used a No 3 morse taper fixed centre from the lathe as the swage tool - This has a 60 degree included angle cone point and fitted just right.
To re-swage the lower end of the push rod tubes the head must be removed. - In honesty I doubt the oil to be running 'up hill' and out of the head.
However before you do that be sure of the following:-
Check the rocker cover gasket is good before you do anything else. There was a batch around that 'shrunk' end to end after being fitted for a while.
Take the cover off and offer the gasket up to it.
I would glue the replacement gasket to the cover before refitting - that makes sure it will not move when the cover is refitted. Do not forget the fibre washers on under the attachment nuts
OR
Is the PCV, mushroom shaped thing connected by rubber tubes to the manifold/rocker cover, working OK. Strip it and clean it and be sure the spring, plunger plate and diaphragm are OK. They do get very gummed up with breathed engine oil over time- spares are available.
You can bypass the PCV.
If you do you must then block up the tube going into the manifold - push a ball bearing or marble in the hose. Then either run a long hose from the rocker cover down into the air stream under the car or into a catch tank over. You could also connect it to the air cleaners like the TR4 had.
REMEMBER - The engine must have some sort of breather tube or oil will P... s out when the crankcase pressure rises.
This removal may affect smog checks if the tester knows what a TR should have.
Hope this is of use.
Cheers
Peter W