shelby 427 aluminum blocks

[blykins]

All aluminum blocks thermally expand. It's just the nature of the beast. Cold clearances are therefore set very tight.

You can use whatever cam/lifters you want.

[Cobra #3170]

blykins is right, perfectly normal condition for Aluminum blocks and heads. My cold valve clearance is .008 n and .008 x when warmed up it is .020 n and
.020 x. The only issue I have had was that I needed a chain tensioner for the cam drive because it was so slack and noisy when cold. A good reason for a nice easy warm up with an aluminum engine.
A belt cam drive will solve this problem, but it is very difficult to package with a dry sump pump.

[4pipes]

Originally Posted by Cobra #3170

blykins is right, perfectly normal condition for Aluminum blocks and heads. My cold valve clearance is .008 n and .008 x when warmed up it is .020 n and
.020 x. The only issue I have had was that I needed a chain tensioner for the cam drive because it was so slack and noisy when cold. A good reason for a nice easy warm up with an aluminum engine.
A belt cam drive will solve this problem, but it is very difficult to package with a dry sump pump.

That's odd. I have a Shelby aluminum block and heads with a flat tappet cam. My lifters are very noisy until the engine comes up to temperature, implying larger clearances when cold.

[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.