The angle of the fins looks wrong when the covers are swapped side to side. The angle is exacty the same when mounted upside down.
Excepting heavily crashed valve covers, I have never seen one warped enough to matter. I have seen dozens and dozens of heads warped enough to matter. '81 on? I have seen '70's heads warp just as much as post 70's heads. The air pump port has nothing to do with it. Minus machining, double gaskets with silicon in between the gaskets is the best solution. Silicon gaskets? Absolute junk! Anywhere!
Yeah, you're right. Junk. It's been a long time since I put them in, and guess what? No leaks. Guess I shoulda doubled up a pair of the stockers with a gob of silicone in between. Nothing like professional!
Why do so many inmates here feel the need to throw people under the bus while disagreeing with them. I never said a gob of silicon. Silicon gaskets themselves? I have seen them working once or twice out of the dozens of times I have seen them patently not working. I have heard that you can actually reuse them IF you clean every trace of oil off of them and the gasket surfaces before re-installation and you are very careful under tightening them. I spend a LOT of time on my own bikes for 46 years now and I don't have the time for silicon gaskets.
Okay, maybe I was a little harsh. If we're going to pick nits, then lets start with silicon vs. silicone. One is sand, the other a nice sealant. I know that you know this. FWIW: I have not cleaned my silicone gaskets any more than I did the stockers, and I still have zero leaks. They solved an issue for me that the stock setup could not, no matter what I did. It's getting too easy to yank your chain SS.
The real reason valve covers leak. Take a head with the problem,its not warping, and set it cylinder gasket surface down on a flat surface. Measure the depth at the 4 main studs to the flat surface. The 2 near the intake side will probably measure around 3.380". The exhaust side should be considerably less especially next to the air injection port. The head is not warping but shrinking down in that area due to being overheated. When heated to a critical temp aluminum as well as most metals shrinks as it cools. The cure is to mill the top surface parallel to the head gskt surface. I have seen them as much as .060" lower.
I knew 'warping' isn't really the right term to use and have tried to explain why before. I have explained it as the center part of the head swelling up but that isn't really right. I was just saying that for how I check the heads by rocking a straight edge over the center part of the head. As you know from actually measuring the damage, it's from the head shrinking, not swelling. Despite always finding it interesting how the valve cover gasket surface always 'warps' and the head gasket surface rarely does (at least not nearly so much), I had never paid that much attention to where exactly the milling machine was taking the most meat off.
What bout use Permatex liquid gasket and forget about the pre-formed hard gasket? I doubled up the gasket and still leak after park for 1/2 hour.
One can see quite clearly where the problem lies by putting the cover on without a gasket. Placing a light below the cylinder will show where the gaps are.
??? What are you trying to say? Mill the head? I prefer not taking off the head, bring it to a mill, mill, just for the leak.
Rather than milling it, could you just lay some fine sandpaper face up on a surface plate and rub the valve cover side of the head around until perfectly flat?
He's right, as usual. There's no way to otherwise flatten the head. If you have no other reason to pull the head, many of the dodges laid out here work, including mine.
What about sanding on a surface plate as I described above? I'm asking, not advocating as I've never tried it in this particular application, but I've used it for plenty of other flat sealing surfaces. Anyone tried it?
If the warpage is under .005" it could work. Anything greater than that makes it hard to hold it flat or parallel.
I agree. I have seen them surfaced on an automotive head surfacer that is like a belt sander. The top surface is level but the rocker shafts are not even close to being perpendicular to the valve stems. Sorta works to stop oil leaks but it aint right.
Real Gasket silicone is great for valve covers. Too soft for some applications, like oil pans gaskets.
I found the leak problem. I accidentally put the washer on the right screw. It was pressed between the head and the valve cover to cause the leak. No leak now. Thank you for the reply.