Valve lash Ford 302

I am having issues with setting the valve lash on my 302 my rocker arms have a bolt to tighten up and not the stud type I have tried to adjust the lash by outting each cyclinder on tdc and adjusting the so the push rod does not turn I cranked the engine over and it ran perfect for a moment till the rocker arm bolts starting to back off so I wen through the whole process again but added blue lock tight to the bolts and still again they backed off after a couple minutes runnin. HElp