I have struggled sealing 2 areas on my Hemis. The first was the intake. Superformance gaskets with high tack has finally dealt with that.

The second area is the valve covers. I have original stamped steel covers on MP/Edelbrock heads. After trying several different things, I have finally found some really cool gaskets. Fel-Pro #1629.

I had already tried the regular Fel-Pros, not knowing that they also made these "performance" gaskets.

Each of these #1629 gaskets is 2 cork/rubber gaskets with a steel mesh laminated between them. They are over 1/4" thick. If these don't do the job, I don't know what will.

One down side to these gaskets, though. The holes in the gaskets did not line up well with the studs. I had to use a Dremel tool to slot most of the holes so that they lined up. The gaskets are plenty wide, so there is more than enough material to make this adjustment.

Amazon has the best price on these, by far.

FYI

I tried this brand, and they seem to really work so far. They are called, Real Gaskets of Tennessee, made from molded silicone, with a fiber core, and are really flexible. But, you have to follow the direction on torquing them, that important. They are made here in Tn.

Don't forget that the spark plug tube depth is affected by the thickness of the valve cover gaskests
another reason I call these pacaderm motors Hemiroids

Always keep that in the back of my mind, Cab.

Dave those are the ones I used with MP aluminum heads and stamped steal valve covers on my mega block. I didn't have any problems with any holes not lining up with the studs thou?

Stopped the external leaks I had.

For what it's worth, they were original equipment on my 472 crate hemi with chrome covers. Had it re-done and builder used superformance versions that leaked. switched back to 1629's and leak free.

I thought of cutting the tube off at the bottom and letting the spark plug go right to the head. Those Milidon tube seals should work keeping the oil out right? Then silicone the top o-ring to the cover. I know once we put those tube seals on no oil got into the cylinders when spark plug was removed.

I had to trim my laminated gaskets the same way to make them fit better with the stamped steel valve covers (mine are the repros). Once I got the good fit I did the RTV on the one side and let them sit overnight flat on the workbench with a little weight on top. Next day I ran a small bead around the inside lip to make sure it was all good, then installed on the head. Nice thing was that I did not have to work it as two items and have the gasket slip out with the RTV mess. I also found that the Orings were not that good of a fit so I took a tube and cover into a place that sells O-rings. Dude was a car guy so he was into helping me find a better fit. #318 is snug on the tube and a firm fit into the valve cover - Zero leaks for the past 5 years or so.

Just to play it safe, before I put the spark plugs in, I went to the hardware store and got 8 12mm washers. The 14mm were too sloppy loose on the plugs . I had to open up the 12mm a little bit, but not too much to get them to fit the plug snug.

Using them between the head and tube will give me more than enough height for the gaskets, which may compress enough over time so that I can safely remove the washers. And if any carbon builds up in the bottom threads, a tap will clean that up easily, if need be.

I used the metric washers due to their smaller OD.