I have a Set of the Cast Thunderbird Valve Covers on my 292. Replaced the Gaskets a few Weeks ago,.Still getting Oil Drips from the back Lower Corner. Covers are tight and Gaskets are not squashed. I seem to recall a few Years ago a Suggestion was made to build up that Corner inside the Cover using Ultra Gasket Maker to alleviate this Drip. I guess that Corner must get more of an Oil buildup until it Drains?. Suggestions?

  

I've had good luck (no leaks) with cork gaskets. Since Y-blocks have solid lifters the covers need to come off at least once in a while. Had them on and off numerous times for that, and other maintenance checks and services.

They are glued to the valve covers. After removal apply clean fresh motor oil to the gasket, let it soak in, and let the gasket "rest" a while. They don't need to be especially tight when installed, that isn't really what makes the seal. Excessive torque distorts OEM type covers. Shouldn't be a problem with cast. They might need a retorque after a heat cycle or two. The specification is only 3-5 ft/lbs, something like that. Start with a light snug torque and kinda sneak up on it. .02c

No telling how old the gaskets I've been using are. At least 25 years. It may be difficult to source good cork gasket today, like everything else.

Are those cast or steel valve covers?

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Cast.

  

I just re-read you first post. I missed the part where you said "cast". Can you check the rear corner of the mating surface on block to make sure its not low. Building up the area with a gasket maker like Ultra Gasket Maker. The oil does pool at the rear when running so that is probably the problem. I've seen people put two gaskets on but as a last resort. If the block and valve covers check out straight I'd try increasing the torque on that side. Don't jump too far up though. When I do valve covers I usually use a 3/8" ratchet held by the head (where the gear is) and tighten them down snug. Usually makes around 20lbs of torque. I've rarely had a leak doing it that way. Maybe you could try upping the torque by 5lbs at a time and see if the leak stops? 

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Neoprene gaskets are thicker, and allow more torque without a permanent crush. Also, axle grease helps seal but still allows easy removal.

6 VOLTS/POS. GRD. NW INDIANA

Ok I will check the flatness of the Block. The Gaskets are making good Contact. I have Wingnuts instead of the regular nuts.I have tightened them down with an extra turn after heating up a few Times. Still drips.

  

I just got 2 Sets of Valve Cover Gaskets from Rock Auto. Mahle which are described as Cork/Rubber Compound. The Ones on mine now are Fel-Pro I think which are listed as Cork.So maybe the Mahle are a better Idea. I guess I will find out. I glue the Gaskets to the Covers with Permatex ultra Black. I am trying to decide if I should coat the Gasket in the back corner area with Permatex Aircraft Sealant or something else? The only place it drips from seems to be that Corner. Suggestions?

  

Mark, lay the valve covers on the heads without the gaskets or the grommets on the studs.  See how close the covers come to the top surface of the head.  Maybe the covers are sitting on the nuts on the studs and not able to compress the gaskets properly.

John - "The Hoosier Hurricane"

Good Suggestion.. I will do that. Thanks John.