The best plan for this cover, as well as the valve cover and the oil pan, is to become skilled at tinsmith work. This in best accomplished with the block on an engine stand. Place the tin on the bare block and tweak it until there are no gaps which a feeler gauge will pass through. The bolt holes are the biggest issue. They need to be mashed flat.
Carl
This is a 216 valve cover. There are no bolt holes except the top. I would have to say this has to be the worst designed piece of tin ever put on a motor. On the side cover I did make sure it was dead flat. Those bolt holes did need flattening. Side cover so far is not leaking.
I had great luck with the valve cover the first time I sealed it. This time I used a silicone gasket thinking I would be able to remove it easier. Going to have to make a second attempt at getting this one to seal.
Don
