Hi all I have a 87 mustang with a fresh 5.0 motor and ecam in it. The problem I have is a little valve train rattle that I have narrowed down to cylinder 4 on the exhaust. It has been converted over to stud mount rockers and has ford racing 1.6 roller rockers. It started rattling so I went through and adjusted all of them and no differnce. Got a stethoscope and narrowed it down to the passenger side and put on a valvecover that i cut a hole in the top off and went through them while it was running and got to that one and and tightened it down a little and it went away for about 10 or 15 seconds then it started again then I tightened it down again same result got quiet for a bit then started rattling again did this several times. So i came to the conclusion that the lifter was bad. Now I have changed that lifter 3 times with the same results moved rockers around pushrods everything I can think and it does the same thing. What in the world is going on here. I have excellent oil pressure 60 cold and about 48 warm with a mechanical gauge. Any ideas or thought would be appreciated thanks