I haven't used a sheet metal cover for years, and correspondingly, have not had a leak in that same time frame.

 

I don’t hate cork gaskets but if you use silicone clean the metal surfaces with brake cleaner, silicone will not stick to an oily surface. I personally like a very thin smear of #2 Permatex.

 

+1 on stamped covers.

I like the spray Permatex gasket cement on top of thicker than stock cork gaskets, nothing between cork and head. Sometimes that works well enough to re-use.

 

Get rid of the steel core gaskets. Even with cast aluminum valve covers they leaked for me. I just use the plain rubber valve cover gaskets and they seem to work fine. With the stamped steel covers, the cork or cork/rubber gasket should work. Just make sure that the metal is straigh, and be sure to use the load spreaders under the bolts (and don't over tighten them).

https://www.autozone.com/external-engine/valve-cover-gasket/p/fel-pro-valve-cover-gasket-vs12869r/67136_0_0?searchText=valve+cover+gasket

https://www.autozone.com/external-engine/valve-cover-gasket/p/fel-pro-valve-cover-gasket-vs50265c/72373_0_0?searchText=valve+cover+gasket

 

I agree w 123pugsy - retired my stamped covers... I am using sce laminated gaskets

 

I’ve used the blue VC gaskets above with LT1 cast aluminum covers. No leaks.

Maybe your leak is a great excuse to get some cool cast aluminum VCs?

 

I didn't have great luck with those on aluminum vc's either. Went back to cork, but I use a thin amount of weatherstrip adhesive on both the vc and the gasket only. Nothing between the gasket and the head, do not over torque.

 

Good luck. I took a set of Edelbrock (tall) off my small block along with the breather assemblies (~$30 each), and the matching air filter assembly. They are cast aluminum. I figured since I did not want them someone would, and afixed them to a piece of heavy cardboard. I mean it's not like they are a wear item. So I figured the retail is over $400, and I figured someone would be happy to give $250 for the set. Heck I could not even get an offer at Good-Guys Columbus last year.

Cast valve covers are way easier to seal.

 

Kind of trying to make the engine look like a L79 would have looked in 66. Heads are aluminum trick flow, VC are what came on a 68 L79, open air filter with closed pvc system. Thanks for all the responces.

 

I discovered, after many years of trying to get mine to seal, that the mating surface on the head is not flat. I had been very particular to make sure the valve covers were perfectly flat with a straightedge and they would always leak a little no matter what gasket/glue combo I tried.
The corners of the cast iron mating surface (factory power pack heads) "drooped" down a little, maybe 1/8", and no matter how much I tried it wouldn't seal.
I ended up bodyworking the valve covers to match the head surface and they sealed finally.

Check your heads for being flat.

 

Always had good luck with Fel-Pro cork gaskets glued to the covers.

 

Chrome will get you home, but it's just too smooth.
Try scuffing the underside rim with sandpaper. Use RTV and place a cork gasket on the RTV.
Then bolt em on and pray.

 

100% cork gaskets can leak through the cork.
Cork / rubber is less likely to leak. You can put a very light film of rtv on the inside face of the gasket so there is no oil contact there. Also a light film on the gasket / cover area.
Make sure the stamped steel covers are flat. Lay them on the head with no gasket to check. Over the decades I am sure someone over tightened them. That will make the area under the bolt higher on the underside.
Rick

 

I ran those Felpro blue gaskets with my "Chevy Power" chrome valve covers and they never leaked. I was quite surprised.

 

The chrome is your issue as 123pugsy stated.
Stay away from !$@#% RTV.
The only places for that are pan corners and intake china rails.
Thoroughly clean the surface with brake clean and glue the gasket to the cover with High-Tack/weather strip adhesive.

Really want it to not leak, clean both surfaces with brake clean and seal with Right-Stuff like a china rail.
Have fun getting them back off much less undamaged if you go that route.

 

I would throw out those blue gaskets with the metal inserts. You spend a lot of money on them thinking you are getting a superior product, but I don't agree. Here are a couple links.

Here is a thread that I had orginally started when I had the same issue. The youtube video was how I did it.


https://www.chevelles.com/threads/valve-cover-leak.1162763/

 

I am using factory Corvair valve cover hold downs. They gotta be factory Chevrolet, aftermarket ones suck as always. You can see the top front ones in this pic.

 

Fel Pro 1604 gaskets. Cork-metal-cork.
Then use weather strip adhesive to adhere them to the valve cover, not the heads.

 

Played this game.
best and easiest way is to
1. glue a cork valve cover gasket to the cyl head.
2. torque the valve cover down to 5 in lbs or the lowest you can do repeatable over night.
3. remove valve cover and glue another cork gasket to the valve cover.
4.torque it down to 20 in lbs over night.
5. you’re done. Unless you want to remove the valve cover and apply a small amount of grease to the non glued side of the cork that touches the cork glued to the head.
In the future you’ll easily be able to remove the valve cover and reinstall it without issue or buying more gaskets. Been doing it like this from day one. Knock on wood iv never had a leak regardless of the valve cover being used.

 

Don’t see how this methods could leak. Should be removable as the 2 cork gaskets should separate easily

Played this game.
best and easiest way is to
1. glue a cork valve cover gasket to the cyl head.
2. torque the valve cover down to 5 in lbs or the lowest you can do repeatable over night.
3. remove valve cover and glue another cork gasket to the valve cover.
4.torque it down to 20 in lbs over night.
5. you’re done. Unless you want to remove the valve cover and apply a small amount of grease to the non glued side of the cork that touches the cork glued to the head.
In the future you’ll easily be able to remove the valve cover and reinstall it without issue or buying more gaskets. Been doing it like this from day one. Knock on wood iv never had a leak regardless of the valve cover being used.

 

Studs help keep gaskets in place.

 

X3 on scuffing the chrome. I prefer the Permatex aircraft or Permatex 300 that comes in a can with a brush in the lid over Indian Head.

 

I run stamped chrome valve covers and the moroso rubber gaskets with the bolt hole dowels and no leaks. I do have the bolts pretty tight.

 

😎 BBC, Cork gaskets glued to stamped Valve Covers, do NOT over tighten. No leaks.

Tried the Rubber Gaskets with cast Valve Covers. Leaked.

 

That’s the plan. So far has worked for me 100% of the time.

 

With the silicone gaskets and chrome or stamped steel valve covers, I spray High tack on the gasket on the valve cover side only, it works 90% of the time. When or if that does not work. I go to an anaerobic sealer, same stuff I use on my transmissions when I rebuild them, it is Loctite 518 that does the trick as well and easier to apply in my book but more expensive. Anyway hope this helps.