so guys i had a knock in my 79. loud and very fast knock. figured it was a collapsed lifter i changed three lifters and its still there. theres alot of play in one of my rockers? could it be a rocker or should i just change all of my lifters?

 

also when its cold and first started in the morning it doesnt knock until its warmed up

 

Have you checked your oil pressure? The word "knock" is subjective as described over the internet, but that's usually associated with the bottom end. Lifters are usually a light tap.