I hope someone can give me some good advise. I have tried the silicone technique that was posted here last year:bead in cover,thenput on gasket. Bead on head then wait I believe 2,3 hours then assembl;e ans tighten lightly, then finish the next day. I still have a leak! So any new advise any one? Also cork or rubber? Also some time back some one posted that NAPA had a soft aluminium manifold gasket ,they say not so, Help.

Dear Herb;

I'm not sure what your question is and there many types of products these days.

When installing 'sheet metal' parts to cast iron most Mechanics do this;

1) Make sure both surfaces are clean.

2) Glue/cement/attatch the gasket (cork/rubber) to the iron surface making sure the bolt holes all match and It's in the proper position etc.

3) Put a generous coat of 'hi temp' grease to the mating surface of the sheet metal to be installed. Install the part and tighten the bolts to spec.

Should this part need to be removed (soon after) the gasket will stick (iron) and not require replacement.

Head gaskets don't (generally) require any special attention or the use of glue/cement, but some may.

Manifold gaskets generally don't either, but there are exceptions. The shiny or 'silver side' goes out on the Chevrolet 6s (most inlines) with aluminum, steel, or cast iron manifolds.

Good luck.

John, thanks for the reply,I should have checked my spelling. Valve cover is my big problem.I was told at NAPA and Carquest that rubber is no longer available for the valve cover gasket. Many have told me get an aluminum cover,but as I haver a Camaro with little hood room a taller cover will not clear my air cleaner(2 1/2") thick flat bottomed by 14" dia. What is so frustrating was when I lived in SOMGLAND and haden't done a thing to my 250 I don't remember it leaking! Go figure. Herb

The suggestion I was told some time ago was to make doubly sure that the mounting edge of a valve cover or side cover is flat and square and not bent even the slightest. This can be accomplished with a piece of soft wood cut to fit and tapped with a hammer or if your a good hammer and dolly man,do that.Also don't over tighten the mounting bolts/screws. They just need to be snug.

Check to make sure the valve cover flange mating surfaces directly underneath the mounting bolts has not been deformed outward. If so the flange areas between the bolts will not get full compression not matter the bolt tightness. You may want to actually peen these areas slightly inward (upward) with some sort of tool, maybe with an oversize punch and socket.

Dear Herb;

You should also contact Larry/Novaman/Twisted 6. He makes valve covers for the 250 and will probably have one "in stock".

Haappy trails.

I know the rubber Valve cover Gasket still comes in the Felpro rebuild kits(gasket set) And to the Best that I know It is Still available as a stand alone. And My Valve cover is taller then the Marine covers So I don't think it would help you anyway.Because of your air cleaner.

Herb, try looking for a Mercruiser valve cover on eBay. They're aluminum, but are the same height as the sheet metal Chevy covers. Just make sure that when you find one that it has the second hole for the PCV valve. They come both with and without PCV valve holes, and if you go to the Marine section of eBay they usually aren't too horribly expensive. Also, another thing you might want to do if you use the sheet metal cover is to get some valve cover hold downs which will help spread out the clamping force and lessen the chance of bending the cover when you bolt it down. Most of them are for V-8's, but a few minutes work with a Dremel and they'll fit fine on your 6 cyl cover. You can usually find them at Auto Zone, NAPA, or Checker/Schucks/Kragen stores, and if you don't want to do that, a 1/4" washer will do in a pinch. I like stainless steel, but it really doesn't matter that much if they're stainless or not.

The marine covers are just a little taller/bigger then Our Stock covers. Which is nice when trying to clear roller rockers.