[trularin]

I preped my valve covers the same way I have been doing it for thirty years.

1. Check all surfaces to be flat and true on each valve cover. If it is bent, fix it.
2. Clean the covers with something that will allow good contact without the gasket being pushed out from film.
3. Pick gaskets that are thick. 1/8" or 1/4" is good. I use cork.
4. Coat the surfaces with 3M weather strip adheasive.
5. Press the gaskets in place and let dry. Make sure they are all the way down.
6. Coat the engine side of the gasket with fibrus grease and install. Do NOT torque down the screws. Seat them after ALL have been started and are in place. Snug them down, but do NOT squish gasket material out from underneith.

That has work all the time, even on flat surface covers with no lip.

Hope this helps.