[Cobra #3170]

I have had two different Aluminum FE's both with roller tappet cams, roller rockers and two different brands of aluminum heads. The first engine had a cold clearance of .006n and .008x and ended up at .020 when hot lashed, the second engine was .008 on both. Valve lash is a very critical dimension so I check it often and it holds these hot and cold dimensions. My cam is fairly radical
(292 D. @.050 and 287 D. @.050 with .780" lift), I don't think that would effect these clearances but perhaps it could, are you sure you are not hearing piston noise? I have heard of some engines that were close to 0 when cold with other cams but I have not personally seen such a condition.