marshal135

Hello,
I purchased a set of the blue silicon over steel valve cover gaskets.
These are the Fel Pro 1635's for Big Blocks.
I read the forum extensively and I'm still unsure if I use a sealant
on the cover to gasket side with these silicon gaskets?
I've read where owners have used weatherstrip adhesive on the gasket to cover side and left the other side dry. Is this just for cork type
gaskets or would you suggest I do same with these silicon ones?
It appears to me if both mating surfaces are clean the silicon gaskets should self seal.
Thanks for the clarification in advance
Marshal

glackore

No, these are not designed for using any additional sealers. The blue "silicone" coating is the sealer. Make sure everything is straight and dry.

qwank

The key to getting a good seal here, is making sure your valve covers are absolutely straight

marshal135

Thank you both for the confirmation.
I felt these should go on dry.
Just got to get em hammered flat.
If I chcek em on a piece of glass with no teetering
back and forth would that satisfy straight enough to seal?
I've got the bolt holes hammered flat now.
Trying to eyeball up the rails is like picking out lumber.
Hope this method proves satisfactory to seal.
It was leaking at the lower rear near the fire wall getting
the bell housing all messy.
Thanks,
Marshal

Rebelrob

Marshal, I have these and they do sweat a little. Meaning some oil does fine its way out the back bottom corners. I had a lot of crankcase pressure as well. I also have cheap sheet metal type valve covers. I was informed I need to upgrade to a good quality cast aluminum valve covers that seal better on aluminum heads. I am no expert on this topic, but I am going to try some pyrmatex gasket maker in some areas and see if that helps.

marshal135

RebelRob,
thanks for the feedback.
I have the orig. fairly heavy guage flash chromed big block
valve covers thet came with the car in 1968.
They seem quality other than the chrome is showing its age.
I think if I get the mating surfaces spotless and the edge surface
as flat as humanly possible I should have some sucess.
I've seen the el cheapo replacement covers for my engine and
they were just not worth experimenting with.
Replacements with the spot welded drippers are about 400 a pair.
I can live with the old ones for now.
Marshal

Steve2147

Installing dry means the surface needs to be oil residue free. Wash all the surfaces with an aerosol brake cleaner and keep oily fingers off the the gaskets and surfaces after you've done that. Glue the gasket to the cover only if you need to hold them in place for instalation and if you do need to glue them use a small bead of 3M weatherstripping cement all the way around. Just enough tohold the gasket in place.

If you read through the threads about the different gasket brands and materials the one common denominator you will find is that someone reports continued leaks with every one of them. The key to a sweat free joint is not which gasket, it's in the procedure. Working on these things in the field back in the day, when you went to remove a valve cover for the first time from it's factory install you had to pry the covers from the head and it would take enough force that the metal cover would bend under your pry bar then they would snap free. They weren't glued down, that's just how well a plane cork gasket sticks to dry surfaces.

Steve g

Rebelrob

Marshal and Steve, yep, I have kept the surface of the head, gasket and vc dry and wiped it down with carb or brake cleaner. I plan to try what you described above or switch to the cork type and see what that does. I also heard from Alan, that you can put some sealant on the screws so oil does not come up thru there.
Marshal, I got my original set of LS7 VC, they were black. They are all chipped and lite surface rust now, but I cannot use them because they are too short and will not clear the roller rockers. They got the drip rails. I need to get them refinished and sell them.

Steve2147

I can't see how sealer on the threads does anything. The gasket goes completely around the bolt hole and it's a blind hole (doesn't go all the way through the casting).. There is no oil near the thread.

If you've been meticulous about keeping it oil free and clean then you want to check your valve covers for flat. I would go to a plain cork gasket. You can get a perfect seal and they're cheap.

Steve g

Edit,
Carb cleaner is not the same as brake cleaner and may leave a residue. I would stick to CR brand Brakleen.

Rebelrob

Steve, there are lots of cork types mr gasket, fel pro, some are .31 inch thick, some are not. I see a set for $10 at the auto part store. That is cheap.

marshal135

I'm planning on getting both mating surfaces spotless and residue free.
I'm taking my time and doing one side at a time.
I think my cork gaskets were orig as mentioned because I had to lift off the VC with a hook tool. They were cork with a silver coating?
Anyway the blue silicon ones are going on dry with new hardware and spreaders. Let you all know how they hold up.
Marshal