i used my origional lifters from my old 100,000plus mustang motor in my new engine , which has a new cam, pushrods,roller rockers, valve springs, so basically the only old things are the roller hydralic lifters. Now, i Do know my rockers are adjusted right. here is my problem, when my car gets hot, the valve train gets really loud, like my lifters arent adjusted correct, or hitting the valve covers lightly. I thought it was my old roller rockers but when i just installed my crane ones, i correctly set the preload, so its not those. the olny thing left is the lifters!? do they do this? OR... some people have said the roller rockers are louder than stock, but damn not this loud right? thanks if you can help