I used the Felpro cork type gasket PN# 1648 for centerbolt, (1604 for perimeter) and after 2700 miles they are leaking a little on the lower long sides. Is there anything better out there? Help please. Thanks.

PS: These are 180 Eliminator heads in a 350 TPI.

Cork?
I always use rubber for the centerbolt covers. They shouldnt ever leak.

I'm a relative amatuer, but on my stock 350 heads and stock centerbolt valve covers, on my new engine, I used the orange rubber ones supplied by the engine manufacturer. Maybe it was a mistake, but first I cleaned all surfaces with rubbing alcohol, then took a tip from an old timer, and glued the gaskets to the covers (not the engine side though), with a very thin strip of black rubberstripping adhesive. Then installed the covers, hand tightening the bolts loosely, while it dried. This prevents the rubber gaskets from coming off the covers everytime you remove the valve covers, and having to re-clean them, and re-center them. (Before I did this, the gaskets would come off when I'd remove the valve covers, get dirty, and sometimes turned.) When I do the final tightening, I'm on the cautious side, leaving them too loose, not too tight and risking warping the covers. I figure I can always tighten them more if they leak, but if you get them too tight, as many may, I think it may cause the leaks. (I haven't yet started my motor, but it's perfectly clean, so I'll know where any future oil comes from). If this is the wrong procedure, guess I'll start over and try again, but I think it's right at this time.

I don't use cork for any gasket if I can help it. Cork blows. Rubber or neoprene are leagues better, especially for valve covers and the oil pan.

Thanks. I'll get these: SCE Gaskets 211079

Please note that, I had to take off my valve covers yesterday, and discovered that the adhesive material I put on the valve covers to hold the gaskets on that side, did not stick. Not sure why. It just dried to the valve cover, and I had to remove the glue with a drill and wire brush attachment. So, when I put them back on, instead I used black RTV to hold the gasket to the valve cover, at 6 points on the cover - 4 on the edges and 1 on each side.

Thanks. I was planning on using black RTV too.