Setting valve lash 428 cbj

[1795]

How do you set the valve lash on an engine when you do not know the cam specs? I have a 1968 428 cobra jet with dove aluminum heads. My mechanic checked the valve lash and it varied from 0-.0024. Luckily the engine only had about 1500 miles on it since the last adjustment on the valves. When we took the valve covers off we did notice that one of the support posts for the rocker arm was backing out.

We had to remove the intake manifold to change the gasket and he said that the heads were more significantly ported than the Edelbrock Performer RPM manifold. I cannot recall the exact number rights now. The rocker arms are top notch, as well as the valve seals. My mechanic, who races, said that the original builder did not spare any expense in building this engine. I was told that it has a competition cam, but we do not have the cam specs. My mechanic was concerned about setting the lash too tight and causing long-term damage to the cam and lifters. He also said, an I have seen in other posts, that sometimes the intake and exhaust are set with a different lash. He set them all to .0014 cold, was thinking about going with .0012 but was concerned that it might be too tight. There was a little chatter early, but then as the engine warmed up it appears to have gone away. He said that we can always tighten them down more if the chatter continues.

So what lash should I use and how to you go about figuring out the cam specs without tearing the engine down?

Thanks.

Jim