I've tried using the silicone valve cover gaskets a couple times and gave up thinking I couldn't get them to stay in place.
https://900designs.zoeysite.com/gasket-valv...h-temp-silicone
So I thought I'd give it one more shot on Mike's car. After taking the valve covers off I could tell the PO had some leaking issues.
Click to view attachment

After running them thru the jet washer 3 or 4 times to most of the adhesive loose. I ran them thru the bead blaster for the final tune up. I decided I try Gasgacinch to try and hold them in place. I let them set up over night.
Click to view attachment

Left went on pretty easy. Only reset a couple time. The right wanted to creep up in the front. So I moved the mini pry bar to that end and worked slowly.
Click to view attachment
Click to view attachment
Gave the gasket a little smear of motor oil before I installed them. I'll give you an update after we fire it up on Friday.

I've never tried the silicone gaskets, but I am sure they will work well.

You PO's method would have been totally fine if he had used about 1/8th the RTV he used. Its the same way I attach the cork gaskets. A VERY THIN smear of RTV along the gasket to the valve cover. Done this way, the gaskets tend to last several oil changes without leaking.

But once you add boogers of RTV, you are introducing all sorts of issues. I'm glad you cleaned that mess out of there! YUCK!

Zach

Thanks for posting. I recently installed the 914 Rubber cork versions which are thicker than stock. I wonder if the silicone and cork versions have the same thickness.

The silicone ones are also slightly thicker too.

Interested to see what your results are. I bought a few sets of these from the original run (I believe he manufactures these differently now) I installed them dry on my autocross car and they sealed up fine initially however once I started pushing it hard at an autox the lack of rigidity allowed them to get sucked in creating a massive oil leak. May be case specific in that I have no head vents on this motor and run it up near 7k RPM, but I went back to their extra thick cork gaskets and have not had a problem.

I have a 2nd set of the silicone ones that I have RTVd to the valve covers installed on a spare set of heads on my work bench. Havent tried them in the car yet as I have not had reason to pull the valve covers after swapping back to the thick cork.

Mike will drive it hard. But it's fully vented.
We'll see.

The silicone will work for high RPM but we do recommend that they are thoroughly cleaned and RTV'd in. The other solution is adding fins to the cover. The cork are bullet proof, the silicone has some flex so under very high negative pressure loads you can displace it is it's not perfectly seated. Prep is key here, must be clean and dry.

adding some small tabs or fins is the trick.