Valve cover gaskets

[0x00fj]

I'm in the process of putting the engine back together. As part of this, I installed new rocker cover gaskets, the "compound" kind shown here: https://www.franzoesische-klassiker-sho ... ts/1003-04

I stuck these to the valve cover lid using Permatex 85420, a solvent-based gasket dressing. Oddly, one of the covers is already leaking slightly (and I haven't even run the engine yet!). Any suggestions as to what to do here? Is this more likely caused by not having stuck the gasket on correctly, or unevenness in the mating surface on the head side?

[Stonehopper]

The compound you have used seems perfectly suitable.
Perhaps the 'dry' side contacting the cylinder head might benefit from a smear of grease. I am reliably informed that white lithium grease is good at this, though some would say any kind of grease.

[0x00fj]

Switched to rubber gaskets and more carefully aligned the covers. The leaks are reduced, but I still get a few drops every drive.

The gaskets themselves seem adequate, which leaves imperfections in the cover or the head. I'm wondering if I should cut my own gaskets out of thicker material, and use a thicker dressing/jointing compound.

@Stonehopper, what is the function of the grease? I've heard it's important to clean all oil off the mating surfaces -- That makes sense on the cover side, where I'm using gasket dressing, but doesn't seem wholly necessary on the head-side.

[Stonehopper]

Grease has been suggested as a material that slows/stops both the slow leak, and prevent a 'dry' gasket from sticking to one face or the other.
Overtightening can cause distortion. Some 2cv valve covers have been tightened so much, they actually touch the rockers! Check for hairline cracks in the covers next time they're off. You never know. They shouldn't leak at all, certainly not to the point of dripping.