I just replaced the valve cover gaskets last week and they still leak oil onto the exhaust manifold and make lots of smoke. I put in rubber gaskets and put black RTV on the valve cover mating surface with the gasket to hold the gasket in place while I put it on the engine. I initially tightened the nuts to 2 ft-lbs and it still leaked. Then I tightened to 3 ft-lbs and it kept leaking. Now I tightened the nuts to 4 ft-lbs but it is still leaking. I dont want to tighten the nuts any more since I think 4 ft-lbs should be more than enough, (or not?). Any tips on how to get both valve covers to stop leaking oil? I sanded the gasket surface of the valve covers when I painted them, but I didnt do much cleaning to the surface of the head. I did scratch off any visible remains of the old gasket, but was I supposed to scrub the metal of the heads with a brush or something?

I assume you're not using the later centerbolt valve covers, and I'll assume you're not using aluminum valve covers. I also think you're not using the factory spreader bars. Here's a link to some aftermarket ones so you can see what I mean: http://www.summitracing.com/parts/PR...7/?image=large
These are not as good as the ones that came stock on most LG4s, but get you a set, get some FelPro rubber valve cover gaskets, throw the RTV silicone in the trash, and start over. Wipe down the VCs and the heads, paper towels are good enough, so long as no bits of paper towel stay in the engine. Then reassemble. Just clean metal and new, clean gaskets. nothing out of any tube. Start at the outside rear, then torque the outside front, then the inside rear, and lastly the inside front. Outside being exhaust side, inside being intake side.

I still have the original spreader bars with the factory valve covers on my L69. Everything you stated is what I used (except that I used the RTV). I guess I'll have to do it again without RTV sealant. Thanks for your reply.

i always use the steel core rubber valve cover gaskets. they seal much better then just plain rubber or cork. Summit Racing sells these for like $12 a set.

I've tried those, I feel they're no better than the rubber ones without the steel core.