Valve Covers

[jb2]

I had valve cover gaskets replaced over the winter (blue felpro) and drove about 100+ miles or so.
I drove it a bit during the winter but mainly started the car in garage every week or so.
I am now experiencing oil dripping down on the exhaust pipe resulting in a lot of smoke.
Without a lift it looks like the oil leak is coming from rear of the back right side head.
(looking into engine). The lower rear and back valve cover nuts were a bit loose.
I tightened very carefully, however still leaking.
Any suggestions would be appreciated.
1966 Mustang Fastback 289

 

[horse sence]

The gasket probably slipped up inside .I usually glue the gasket to the valve cover ,it makes it easier to install and keeps the gasket from slipping and causing an oil leak .

 

[7991LXnSHO]

Even the best gasket leaks if it slips or if the cover is bent. On another car known for leaks, I used high temp silicone on both sides of the composition gasket. That stuck so well, it still might not need the bolts after drying.
The rubber gaskets with metal rings for torquing the bolts just right sound like a good idea with flat valve cover flanges.