If you truly want to stop your gasket leaks for once and for all, there are 3 things you can do. Two you know about and one may be a new idea for you:
1. remove all old gasket material from your valve cover 2. carefully straighten the cover's mounting surface very well. Especially at the bolt holes where they always are deformed. 3. go to a hardware store and purchase some 3/16" thick aluminum. Take with you one of your valve cover screws and purchase 4 screws that are about 1/4" longer than the original but with the same thread. You can get 4 washers to use with these if you wish. Your piece of aluminum ought to be apx. 2 inches wide or so to allow you room to cut. Now using cardstock paper, make templates of the inside edge of your valve cover...where it lips upward. Make your template so that it starts at the end of the channel (where the valve cover turns the corner, so to speak) and separates in the center, leaving about 1 inch space at the center. This will produce for you pieces that are a bit less than 1/4 inch wide with little dimples. You will have 4 template pieces now...2 for each side. Using a pencil or a fine-tipped Sharpie marker, trace around your templates onto your aluminum. Now with a saber saw and a metal cutting blade carefully cut out the pieces and use a common file (not coarse but more fine) to dress the edges if needed. Now paint them the same color as your engine. And finally carefully bend the pieces you've cut so that you have a flat part where the screw will be and the ends will taper downward at about 10 or 15 degrees. What you've made are called spreaders and ought to look like the images below. Now glue your new gasket to your head (not the valve cover) using a good sealer like Permatex Aviation sealer and install the new gasket. Now install your valve cover and your new spreader pieces. You'll have to press down on the spreader in the center to get the thread started. Do this for all four screws and when you're finished (if you've done what I said), I promise you will not have valve cover leaks again. I made these about 3 years ago and I haven't seen a single drop outside the valve cover.
If you are really industrious and have the aluminum, I suppose you could do the same thing for your valve lifter cover, but I just sealed mine well and it seems ok.
I've thought about making these as a Stovebolt product, but never have. Ideally I think somebody with an industrial CNC laser would be best set up to do this.
Grease Monkey, Moderator General Truck Talk & Greasy Spoon
He’s saying go buy a cast aluminum valve cover, install it, torque it and be done.
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne 4dr 230 I-6 one owner (I’m #2) “Emily” ‘39 Dodge Businessmans Coupe “Clarence”
"I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
59 rebuild I understand that some guys want to stay as original looking as possible,I lean more to the hot-rod aftermarket look. It looks best to me with aluminum valve cover,HEI,split manifold,aluminum intake,and I guess I am the only one in America that runs their truck on straight propane!! As john Milliman says let's all have our fun !!! I sure do !!!!!