[steve25]

I have never liked cork composition gaskets!

There made of particles that hopefully stay bonded together and after enough time or being tightening they don't!

If I am in a position where I have to use a cork gasket I first seal it on both sides with a film of form-A- gasket and I let it dry fully before I install the gasket.

If you have a wavy stamped steel valve cover in use then that's a very likely cause of your leak, dispite using a thick gasket.

[mgarblik]

Very common leak area among the many. Cork gaskets are my go to gaskets. I have best luck with them. It's the cheap, paper thin covers and the lack of proper number of fasteners that are the root cause. Make sure you have a high quality, newer gasket in place. I tack it to the cover and install clean and dry on the head. Make sure the flimsy gasket rails are as flat s possible. Hammer and dolly as necessary to get them flat. Use Moroso load spreaders if necessary and the leaks will go away. They don't look 100% stock but are better than an oil leak. I currently have 1 load spreader in that right rear lower location. It was the only way I could get that cover 100% dry. Good luck. Making a Pontiac V-8 leak free is quite an accomplishment. The "Harley of the V-8 engines". Lots of places for leaks.

[nUcLeArEnVoY]

I actually have better luck with cork gaskets. I tried the thick cushiony edelbrock gaskets made of the foamy rubber material and they leaked like sieves.

The key is to have a straight valve cover for one. Rather than use a hammer and dolly, just position each warped area into a bench vise using the perpendicular lip as a stop, and press into it as tight as you can to flatten it out. It won't work on all types of bench vises but it's the best way to truly flatten them out.

I also use load spreaders for some extra insurance. Don't care if they don't look stock - sometimes we gotta do what we gotta do.

[Dragncar]

Originally Posted by nUcLeArEnVoY

I actually have better luck with cork gaskets. I tried the thick cushiony edelbrock gaskets made of the foamy rubber material and they leaked like sieves.

The key is to have a straight valve cover for one. Rather than use a hammer and dolly, just position each warped area into a bench vise using the perpendicular lip as a stop, and press into it as tight as you can to flatten it out. It won't work on all types of bench vises but it's the best way to truly flatten them out.

I also use load spreaders for some extra insurance. Don't care if they don't look stock - sometimes we gotta do what we gotta do.

I have some thick Edelbrock gaskets. I pulled one off a valve cover that I gorilla snotted on and its cork. Kind of stiff too.
Not sure if they are going to leak or not.
I will have some Fel Pro cork as backup.
O have some Cometic gaskets on my fabricated valve covers and they are pretty thin.